OpenCitations blog – The blog of the OpenCitations Infrastructure

#1 Who’s using OC? The dblp computer science bibliography

This blog post is the first of a series which will highlight some of the ways OpenCitations is currently adopted and used by the community. This series also gives us the chance to thank our users for trusting OpenCitations and for giving us the opportunity to improve our services through their feedback. With you, OpenCitations is a drop generating countless circular waves of innovation in research.

The dblp computer science bibliography (https://dblp.org/) is the on-line reference for bibliographic information on major computer science publications, with the mission “to support computer science researchers in their daily efforts by providing free access to high-quality bibliographic meta-data and links to the electronic editions of publications”.

Currently, dblp indexes over 7 million publications, published by more than 3.4 million authors. Despite the small team of editors from the Schloss Dagstuhl, which run the service, in the last few years, dblp has grown from a small-scale server to a service used by thousands of people worldwide.

In 2022, they released the dblp Knowledge Graph, and in June 2024 they released a first major extension to the dblp KG by adding publications venues (e.g., journals and conference series) as first-class entities to the graph. This new release also includes a new property (i.e. dblp:omid) to link dblp publications to their OpenCitations Meta Identifier (OMID). This ID is crucial for making use of open citation and reference data available in OpenCitations since it is the internal identifier we use to identify every bibliographic entity (publications, authors, venues, etc.) stored in our system.

Indeed, the dblp computer science bibliography doesn’t collect and store citation information itself, but instead ingest directly the open citation data released by OpenCitations. Using the linkage provided by OMID, the dblp users can perform citation analyses using its SPARQL query service.

Dblp has published a detailed guide to help “beginners” find data in the dblp Knowledge Graph, and you can find it here.

If you are looking for more information about the dblp project, please explore their exhaustive F.A.Qs.

Thank you, dblp, for reusing OpenCitations data!

Remembering David M. Shotton, Founder and Co-Director of OpenCitations

The Founder and Co-Director of OpenCitations, Prof. David M. Shotton, peacefully passed away on Saturday, 18th May, after a long battle against illness. With his death, OpenCitations lost a Director, a Mentor, and a Guide. OpenCitations wouldn’t have existed without David’s foresight, which led him to design the first prototype of OpenCitations as a one-year project founded by JISC in 2010. Since then, David has closely followed the developments of his open infrastructure, to whose growth he has dedicated his considerations and intuitions almost until his last months. In one of his last authorial posts on this blog, he traces the history of OpenCitations, and his words show the pride of having seen the “little acorns” grow into a globally validated and trusted infrastructure.

It’s impossible to overstate the gratitude that the entire OpenCitations team feels for David. OpenCitations, a living testament to his vision and guidance, is a result of his leadership. We were privileged to accompany David on this journey, witnessing the volcanic energy of his mind and benefiting from his wisdom and integrity.

We want to dedicate this space on the blog to the words of those who knew him as a colleague in the context of his work in OpenCitations and the Open Science ecosystem but above all as a guide and a friend:

David was an early, earnest, and ardent supporter of open. He was also fiercely committed to sustaining what he helped to build, and he worked tirelessly to ensure that OpenCitations would be resilient and active as a long-standing, trusted model and resource for others. His work on succession planning started many years ago, and I remember well when he first contacted me and Educopia in hopes that we could help the OpenCitations team to think through specific risks and how to plan to overcome them. He was equal parts determined and creative, and the stability and resilience of OpenCitations in this moment is one testament to his care and thoughtfulness. He will be sorely missed as a leader and perhaps also as a bit of a sage in this field.  Katherine Skinner (IOI)

David was an inspiration.  Through each discussion, I felt his passion for our work and constant interest in learning from his friends and colleagues.  He was a role model to me, a great human being, and his impact is felt across the global research infrastructure space. John Chodacki (UC3)

David’s importance for our work of course cannot be overestimated. I think I was introduced to David’s ideas and his way of thinking when I read his 2013 piece in Nature. This piece had a profound impact on my own ideas. If David had not written his 2013 piece, and if OpenCitations had not been established, my world would have been a very different one. I will remember David as someone who was always very gentle and generous. I still remember welcoming David and Silvio at CWTS in Leiden. David and I had a private chat and I complimented him for all the important work he was doing. David seemed to feel a bit uneasy about this and he repeatedly said that it was mainly Silvio, not him, who deserved to be complimented. My last contact with David took place earlier this year, when we were exchanging some emails. I was impressed by the positive tone of David’s emails. Rather than being sad about being terminally ill, he was thankful for all the things he could still enjoy and for everything life had offered to him. Ludo Waltman (CWTS)

Three phases characterised my path with David. First, he was a mentor. When I was a PhD student at the University of Bologna, I was lucky to visit David’s lab at the University of Oxford. This period was crucial for me – on the one hand, for my PhD thesis and, on the other hand, for my academic growth and career. Then, after my PhD graduation, David became a colleague with whom we discussed and worked on several research topics that resulted, in the end, in the creation of a new instance of OpenCitations at the University of Bologna. This seed brought us where we are today. Finally, and most importantly, he was one of the dearest friends I’ve found in my life. Always supportive, constructive, and delicate in every situation – and that, I confess, is the part I miss the most. We have lost one of the most passionate and bright minds in the Open Science community, who has left us an enormous legacy we are called to preserve for future generations. I can only thank you, David, for what you donated to me and the whole community. Silvio Peroni (University of Bologna / OpenCitations)

I am saddened to hear the news of David’s death. I worked with David on a number of projects when I was at the Bodleian Libraries, University of Oxford. I was involved with the institutional repository for publications and data, and developing related university services. David was a huge advocate of Open Access in its many guises: for publications, data, and infrastructure. He was a tour de force with a phenomenally quick and creative mind. He saw opportunities for funding to develop innovative tools and services around research data and publications, and was able to enthuse others to participate. I used his exemplar semantic data paper from 2009 (Reis, R.B. et al, 2009) many times when discussing data repositories, open access and the possibilities for 21st century publication models. He always had his eye on the future and the direction of travel for open services and infrastructure – he was inspiring. My condolences to his family, friends and colleagues. Sally Rumsey (Formerly: Head of Scholarly Communications and RDM, Bodleian Libraries, University of Oxford)

A note from myself and also on behalf of colleagues in the Oxford e-Research Centre, who remember David as a friend and colleague during his time here. We have all been saddened to hear this news.
David and his team came to OeRC in 2013 (from the Department of Zoology) and were a most welcome addition, as David was a very significant voice in open science and scholarship – and an inspiration to our growing community, through his appearances at many meetups and gatherings. I had worked with him previously, in the Semantic Web and in the authoring of the FORCE11 Manifesto – David was one of the organisers of the Dagstuhl Seminar which initiated this important movement. I was proud later on to be able to play a small part in supporting the OpenCitations work.
David was also one of the key people in Wolfson College, along with Donna Kurtz and David Robey, who championed “digital research”. The collaboration with Donna, combining image expertise across sectors, saw the launch of a pioneering Linked Open Data project: the CLAROS virtual art collection. Stemming from this, David brought his enthusiasm to support an international collaboration with Chinese data, which continues today as part of the successful OSCAR advanced research centre.
The sad news has, with very fond memories, brought the original team back in touch again – including Graham Klyne and Jun Zhao who came with David from Zoology and have also made important interdisciplinary contributions. We all owe David huge gratitude for his passion, energy and insight, for all his support, and for the very significant influence he had on his colleagues and community. David De Roure and the colleagues of the Oxford e-Research Centre

I am saddened by David’s passing, but I’m sure his spirit lives on in the many lives he has touched. I was for several years a member of his Image Bioinformatics Research Group in the Zoology department of Oxford University, where he set a path for my late-stage career change to working in academia. He supported and embraced an open style of working that complemented the then-nascent open access movement for research publication. His visionary early adoption of web data technologies was rooted in a genuine concern for preserving access to important bioinformatic data that were at risk of being lost in the transition to digitization of research; he would often refer to his collection of micrograph slides that contained original recordings from his seminal work in unravelling biochemical structures. And I recall his kind support of many researchers who intersected his orbit and went on make significant contributions of their own. I feel that OpenCitations is a fitting legacy of David’s work, reflecting his scientific and scholarly concerns, and also his enthusiasm to engage a wide range of stakeholders. Graham Klyne (formerly Research Software Engineer at University of Oxford)

This post aims to be a virtual wall where anybody who has met or known David in the context of his lifelong commitment to Open Science can leave a message. If you wish to have your thoughts on David published here, please email comms@opencitations.net.

Find OpenCitations on Infra Finder, a new tool to discover and support Open Infrastructures

If you are a leader of a Library or a Research Institution and would like to learn more about the existing open infrastructures that could help your institution to evolve in the research environment, but you don’t know where to look for, you can now use Infra Finder, a brand-new tool aimed at foster discovery, adoption, and investment for open infrastructure services. Infra Finder is launched by Invest in Open Infrastructure (IOI), and is designed to be the go-to resource for anyone navigating the complex landscape of infrastructure services and standards enabling open research and scholarship.

The tool stems from the feedback collected from the community after the launch, in 2022, of the Catalog of Open Infrastructure Services pilot project in 2022, from which IOI decided to re-envision what outcomes they could affect and rethink what solutions could look like, also by furthering the Open Science principles conveyed by UNESCO’s Recommendation on Open Science, the Principles of Open Scholarly Infrastructure, and other Open Science initiatives and guidelines.

We are happy to announce that OpenCitations is among the 56 infrastructures which have accepted IOI’s invitation to be included in this first release of Infra Finder. During its development, IOI team has been constantly collecting feedback from the infrastructures involved, and has conducted user testing to understand how different people might approach it. In OpenCitations we believe that Infra Finder could serve as an helpful tool to make OpenCitations and the other infrastructure services more visible to a wider and diverse community. Infra Finder allows users to easily find and compare the catalogued services, and its intuitive use could work as a starting point towards the creation of a greater awareness of existing open infrastructures, thus leading users to further explore their features and services and, hopefully, to consider the possibility of support their sustainability.

IOI is currently planning to include new services in Infra Finder: if you are part of an organization that would like to be included, you can apply by filling out their Expression of Interest form. IOI will give two identical webinars to share with the community more details about the background and features of Infra Finder and on how interested infrastructure services can express interest in being listed. Register here to the either slot:

May 2, 2024, 1600 UTC / 12pm Eastern

May 3, 2024, 1400 UTC / 10am Eastern (in your time zone)

The IOI blog post for the launch is available at https://investinopen.org/blog/infra-finder-your-hub-for-finding-infrastructure-services-enabling-open-research-and-scholarship

OpenCitations supports the Barcelona Declaration on Open Research Information for a fundamental transformation in the research information landscape

Research Information can be defined as an information (sometimes referred to as metadata) relating to the conduct and communication of research. This includes, but is not limited to, (1) bibliographic metadata such as titles, abstracts, references, author data, affiliation data, and data on publication venues, (2) metadata on research software, research data, samples, and instruments, (3) information on funding and grants, and (4) information on organizations and research contributors. Research information is located in systems such as bibliographic databases, software archives, data repositories, and current research information systems.

Decision-making in science is often biased by the typology of research information, and too often is based on closed research information, which is locked inside proprietary infrastructures and run by for-profit providers that impose severe restrictions on the use and reuse of the information. As a consequence, errors, gaps, and biases in closed research information are difficult to expose and even more difficult to fix. Indicators and analytics derived from this information lack transparency and reproducibility. Decisions about the careers of researchers, the future of research organizations, and ultimately the way science serves the whole of humanity, depend on these black-box indicators and analytics.

There is an urgency for a fundamental change in the research information landscape towards openness. Indeed, open research information enables science policy decisions to be made based on transparent evidence and inclusive data and information used in research evaluations to be accessible and auditable by those being assessed. It makes it possible for the global movement towards open science to be supported by information that is fully open and transparent.

Today, over 40 organizations, including the University of Bologna, are committing to making openness of research information the norm and to lead this change in the research information landscape. The signatories of the Barcelona Declaration on Open Research Information commit to taking a lead in transforming the way research information is used and produced, to make the openness of information about the conduct and communication of research the new norm.

The full text of the Barcelona Declaration is now publicly shared on barcelona-declaration.org and presents the commitments that all the signatories of the Declaration adhere to, namely

To make openness the default for the research information we use and produce;
To work with services and systems that support and enable open research information;
To support the sustainability of infrastructures for open research information;
To support collective action to accelerate the transition to openness of research information.

In addition to the signatories, the Declaration has been supported by several organizations providing data, services and infrastructures. OpenCitations has declared its support to the Declaration, together with AmeliCA, Crossref, Curtin Open Knowledge Initiative (COKI), DataCite, EuropePMC, DOAB, DOAJ, Europe PMC, Liberate Science GmbH, OAPEN, OpenAIRE, OurResearch, Redalyc and ROR. OpenCitations believes in the Declaration as a starting point for a substantial change by promoting values which OpenCitations fully supports, as stated in the words of our Director and Associate Professor at the University of Bologna Silvio Peroni:

Since its creation in 2010, OpenCitations has always advocated and actively worked to produce open research information and develop infrastructural technologies to maximise its sharing and reuse in different applicative contexts. Thus, we embrace the Declaration’s goals and commitments and look forward to working with all the signatories to foster the use and production of open research information.

Prof. Silvio Peroni has been a part of the initial team of over 25 research information experts, representing organizations that carry out, fund, and evaluate research, as well as organizations that provide research information infrastructures, which first prepared The Barcelona Declaration on Open Research Information. The group met in Barcelona in November 2023 in a workshop hosted by SIRIS Foundation. The preparation of the Declaration was coordinated by Bianca Kramer (Sesame Open Science), Cameron Neylon (Curtin Open Knowledge Initiative, Curtin University), and Ludo Waltman (Centre for Science and Technology Studies, Leiden University).

As of April 15, 2024, the list of signatories involves universities and other research performing organizations such as Αthena Research Center (Greece), Charles University (Czech Republic), Coimbra Group (international), Hamburg University of Technology (Germany), I-CERCA – Centres de Recerca de Catalunya (Spain), Instituto Brasileiro de Informação em Ciência e Tecnologia – Ibict (Brazil), Leiden University (Netherlands), Museo Galileo. Istituto e Museo di Storia della Scienza (Italy), Otto-Friedrich-Universität Bamberg (Germany), Sorbonne Université (France), Spanish National Research Council – CSIC (Spain), Udice – French Research Universities (France), UnilLaSalle (France), Universidad de Antioquia (Colombia), Università di Bologna (Italy), Universitat de Barcelona (Spain), Universitat Politècnica de Catalunya (Spain), Université Grenoble Alpes (France), Université Le Havre Normandie (France), Université Paris Saclay (France), University of Coimbra (Portugal), University of Groningen (Netherlands), University of Maribor (Slovenia), University of Milan (Italy), University of Poitiers (France), University of the Azores (Portugal), University of the Balearic Islands (Spain), University of Turku (Finland), Vrije Universiteit Amsterdam (Netherlands); research funding organizations and governments, including Bill & Melinda Gates Foundation (US), Catalan Foundation for Research and Innovation – FCRI (Spain), Dutch Research Council NWO (Netherlands), French Open Science Committee (France), French National Research Agency – ANR (France), Fundació Internacional Josep Carreras (Spain), Région Normandie (France), Regione Toscana (Italy), ZonMw (Netherlands); other organizations: Consorci de Serveis Universitaris de Catalunya – CSUC (Spain); EOSC Association (international), Latin American Council of Social Sciences – CLACSO (international), National Open Research Analytics, Technical University of Denmark (Denmark), State Scientific and Technical Library of Ukraine (Ukraine), TIB – Leibniz Information Centre for Science and Technology and University Library (Germany), UK Reproducibility Network – UKRN (UK).

There is a need for global and concrete action to reach the tipping point in the transition from closed to open research information, and the Barcelona Declaration on Open Research Information is open for signature by all organizations that carry out, fund, and evaluate research to support this transition.

If you want to learn more about the Barcelona Declaration, join us in the launch webinar on April 23, 1.00-2.30pm CEST. Click here to register for the webinar.

You can also keep yourself up to date by following the Barcelona Declaration’s social media channels:

LinkedIn: https://www.linkedin.com/company/barcelona-declaration/

Mastodon: https://mastodon.social/@BarcelonaDORI

X: https://x.com/BarcelonaDORI

Looking back to look ahead: OpenCitations’ achievements in 2023

The first month of the new year has almost come to an end, and we at OpenCitations have dedicated these weeks after the holiday season to retrace the progress we reached as an open infrastructure throughout 2023, an activity that has become a tradition in the past few years. Looking back to the achievements has proven to be a great practice for our team not only to honour and celebrate the success, but also to visualize the points to focus on to best serve our community when planning future activities. During 2023 we have reached numerous milestones, which can be summarized under the two main topics: technical developments and new connections.

Technical Developments

1. New sources

At the end of 2022, we had enriched our collection with two more sources, PubMed and DataCite, which were added to Crossref. During 2023 we completed the integration between OpenCitations and the OpenAIRE Graph as concerns open bibliographic and citation data, and in December we included the DOI-to-DOI citation links derived from the Japan Link Center (JaLC). As a result, by the end of 2023, OpenCitations counted almost 2 BILLION open citations available in its collection.

2. A brand-new workflow for an easier consultation

The progressive integration of new sources is one of OpenCitations’ main objectives. However, the recent source increase made it necessary to design a new ingestion workflow to facilitate their management. In November 2023 OpenCitations launched the new workflow, designed to produce just two comprehensive collections: OpenCitations Index, collecting open citation data, and OpenCitations Meta, containing open bibliographic metadata of citing and cited entities involved in citations. This evolution is making it simpler for OpenCitations users to consult the data maintained by our infrastructure without reducing the information content and accuracy. 

New connections

3. A great event for the community

In October 2023, OpenCitations hosted the Workshop on Open Citations and Open Scholarly Metadata 2023 (WOOC 2023) in the historical location of the University of Bologna. After two online editions, it was exciting to meet in person the researchers, policy makers and service providers who in the past few years have collaborated with OpenCitations in many ways. For two days, almost 80 people from all around the world gathered to discuss the theme “The value of open scholarly metadata for Research Assessment purposes”. The event gave us a picture of a young and enthusiastic research community, aiming to collaborate among different countries to spread the message “Open Science is Better Science”. If you couldn’t attend the workshop, but are interested in the theme, you can find all the presentations from WOOC 2023 on Zenodo. Stay tuned on the WOOC X account and website, we will announce the 2025 edition later in 2024!

4. New and old partnerships

OpenCitations’ main activities, besides the technical development, are tied to its participation in R&D and funded projects. Since 2019, we have started building a network of collaborations all around the world with institutions which share the same Open Science values. In 2023, our involvement in the SCOSS 2nd funding cycle has come to an end. In the last four years SCOSS has worked as an international showcase for OpenCitations, making it possible for us to get known by many institutions on an international level. We are now proud to keep on collaborating with SCOSS within the SCOSS Family network, a community of practice gathering all the OS infrastructure involved in the SCOSS funding cycles. During 2023, the SCOSS Family was involved in four internal sprints dedicated to planning four actions – collectively advocating the importance of open  infrastructure, communications kit for ‘the post-SCOSS phase’, collective self-assessment towards POSI, and map open science infrastructure ecosystem including SCOSS infrastructures – and the initial outcomes were presented in the Scoss Family Public Webinar 2023. The SCOSS family will continue its activities throughout 2024.

In 2023, we also celebrated the update of the Principles of Open Scholarly Infrastructure (POSI), as a result of the work conducted since 2022 with the “POSI-Adopters” group to make the principles clearer and more inclusive. In June, the OpenAIRE-Nexus project, started back in 2021, formally came to an end, with the release of the index of citations from OpenAIRE. OpenCitations is part of the OpenAIRE Catalogue, which also links to the exhaustive and engaging materials we produced within the project. However, we continue to meet the familiar and friendly faces from the OpenAIRE team in the meetings of GraspOS, a project which started in January 2023 involving several European Open Science institutions, services and infrastructures. In GraspOS, OpenCitations is involved as one of the Data Asset Sources, which provides both the raw and the structured data that can be used to directly support OS-aware RRA processes or to calculate indicators or collect evidence that can be of value in these processes. The researchers from OpenCitations and the University of Bologna are contributing to GraspOS by developing a tool for the extraction of citation data from PDFs, enriched with additional information on the reasons for citing (because the citing entity reuses a method described in the cited entity, for agreeing with the claims of the cited entity, etc.) through the implementation of machine-learning systems. Also, together with GraspOS, OpenAIRE, and many other Coalition members, the OpenCitations personnel at the University of Bologna is among the participants of the CoARA Working Group Towards Open Infrastructures for Responsible Research Assessment (OI4RRA), to work on enabling the research community to be in full control of the data and indicators it relies on in assessments. OpenCitations is always seeking interest from new institutions, and we are proud that our visibility is boasted by some reliable catalogues including the OpenAIRE catalogue, the EOSC Marketplace and, from 2023, also the JISC Catalogue. And soon you’ll find us in a new tool – stay tuned to find out!

5. Our way towards sustainability

OpenCitations is increasingly gaining a prominent role in the community, establishing itself as a key player in changing research evaluation practices towards greater openness and equity. In recent years, OpenCitations has grown a lot both technically and in popularity, and for this we want to thank the number of members and donors who, even in the last year, have decided to support us and believe in our infrastructure. During 2023, our two Internal Working Groups “Governance Evolution” and “Community Building”, thanks to the participation of some members of the International Advisory Board for OpenCitations, reflected on the sustainability of OpenCitations, discussing strategies both at the management and communication level to ensure the integration of new actors into its subsistence. The groups will continue to meet throughout 2024, and some of the results will be released in the coming months. However, there is still a long way to go towards sustainability, and OpenCitations’ existence still relies on community funding, which is why OpenCitations still needs support: if you are looking for more information on why and how to support OpenCitations, you can read our recent call for action here. Thank you!

6. Enlarging our team

It is thanks to the support received that OpenCitations was able to develop its yearly activities, and we are happy to announce that in 2023 a new software developer, Elia Rizzetto, and a new PhD student, Francesca Cappelli, have joined our team to make this progress possible. The OpenCitations team now has a total of 12 members, including research fellows, PhD students, MA students, a Reseach Manager, an Assistant Professor and OpenCitations’ Directors. The number is expected to grow soon, as OpenCitations has recently released a call for the hiring of a System Administrator for technical infrastructure management.

As can be seen from this brief (and detailed) report of some of the developments that have marked our 2023, OpenCitations is increasingly emerging as a community-based and community-guided infrastructure organization, in which there is an indissoluble link between technical progress and the network of people who guide the planning, work on implementation, and use or promote our services. Throughout 2024, OpenCitations aims to focus even more on harmonizing the relationship between the technical infrastructure and the community, developing more intuitive ways of accessing services and communications, and continuing to weave relationships with new research groups. We look forward to seeing what the year ahead will bring with it, and we hope you will continue to be with us.

A new revolutionary workflow for a unified collection of citations: say hello to the OpenCitations Index

Blog post by Ivan Heibi (University of Bologna), Arianna Moretti (University of Bologna) and Chiara Di Giambattista (University of Bologna).

In the past five years, the OpenCitations data has been enriched with numerous new indexes of open citation data from different sources. However, the quantity and diversification of the ingested information have raised several issues, which recently made it essential to conduct a complete revision of the ingestion workflow. The result was a revolution in the way OpenCitations data is delivered. In this blog post, we will explain the context and challenges raised by the old procedure. Then, we will present the new ingestion workflow, designed to produce just two comprehensive collections: OpenCitations Index, collecting open citation data, and OpenCitations Meta, for the open bibliographical metadata.

Once upon a time, there were five OpenCitations indexes…

In 2018, OpenCitations released the kickoff version of its first citation index, COCI (citations from Crossref), which contained around 300 million citation links derived from the subset of the reference lists in the Crossref database, where citing and cited entities were identified using Digital Object Identifiers (DOIs). COCI gathered citations with associated metadata in compliance with the recommendations from the Initiative for Open Citations (I4OC) that citation data should be structured, separable, and open, thus marking a turning point by providing a disruptive and free and open alternative to earlier sources such as Google Scholar, which provided freely accessible data although not downloadable, and Web of Science or Scopus, which demanded paid access.

In a short time, COCI became a competitive and trusted index of citation data, used by numerous institutional repositories, including B!son and Optimeta. In 2021, COCI was taken into account in a comparative study with the most relevant sources in the landscape, including the proprietary ones, which showed its coverage approaching parity with those of the other sources involved in the analysis (Microsoft Academic, Scopus, Dimensions, and Web of Science). At the time of its most recent update in January 2023, COCI counted more than 1.4 billion citations. The reason behind this outstanding number lies in several factors, including Elsevier’s endorsement of the Declaration on Research Assessment (DORA) in December 2020, leading to the open release via Crossref of the reference lists of the articles published in all its journals, and confirming the value of initiatives such as the Initiative for Open Citations (I4OC).

However, before this change of heart, in 2019 OpenCitations had tried to narrow the open citations coverage gap by launching its second index, the Crowdsourced Open Citations Index (CROCI). This index allowed publishers and scholars to contribute directly by uploading crowdsourced open citations into the OpenCitations infrastructure.

In December 2022, a new concrete step towards a factual plurality of OpenCitations indexes was taken by the ingestion of new data sources into the infrastructure, with the publication of the inaugural dumps of DOCI (citations from DataCite) and POCI (citations from PubMed). In June 2023, the first version of the OROCI (citations from OpenAIRE) dump was released too, and JOCI (citations from JALC) is expected to be available by the end of November 2023, for a total of five collections from different sources.

Why a new workflow? The issues with multiple sources management and new challenges

While having such a variety and richness of indexes helped present the extent of OpenCitations sources, the recent increment in the number of sources and the diversification of data integrated led to two primary issues:

1. the necessity to handle the ingestion of new identifier types in a DOI-based software infrastructure, and
2. the consequent possibility of encountering the same citation expressed by several sources with different identifiers.

Moreover, it soon became evident the need to optimize the reuse of the already developed software components to facilitate the metadata crosswalk processes between the new sources’ data models and the OpenCitations Data Model, with the aim to define a functional and easily extendable workflow to be easily reused when it comes to incorporating new data sources, which should be:

1. sufficiently generic to establish a globally unique procedure;
2. customizable enough to capture the necessary information within each of the specific data models and formats.

As a solution, we decided to use OpenCitations Meta, the new OpenCitations database and tool for managing bibliographic data related to the publications involved in the citations. OpenCitations Meta makes it possible to assign each entity involved in a citation an internal identifier, nominally the OpenCitations Meta Identifier (OMID), to which all the associated persistent identifiers of the same publication are redirected.

As a result, the allocation of an OMID for each bibliographic resource also enabled the unambiguous identification of each citation, regardless of the persistent identifier schema originally used by the data source to identify the resources. This approach allowed us to perform data deduplication and finally make all the sources’ contributions converge into a unified index containing all the unique citations managed by OpenCitations, expressed as OMID to OMID citation links.

The revised workflow

The new workflow is based on three main components with the benefit of optimizing the process both in terms of computational cost and in terms of flexibility. As shown in Fig. 1, in a preliminary step, source-specific software converts the input dataset – structured according to the source data model – to extract two OpenCitations Data Model compliant data collections in tabular format for bibliographic metadata and citation data, respectively.

The following steps are common to the process of each dataset.

STEP 1: The bibliographic metadata collection is used as input for the META software. At this stage, it is checked whether or not the bibliographic entities have been previously integrated into our infrastructure (coming from other data sources). If so, the existing OMID is linked also to the new alternative identifiers of the new bibliographic resources. New metadata values, if any, are also integrated. A new OMID identifier is produced for entities never previously encountered, uniquely representing the bibliographic resource in OpenCitations. The outputs of the process are: (I) an updated version of the OpenCitations Meta collection that also includes the metadata of the bibliographic entities provided by the new source, and (II) a collection of provenance data. An internal database is constantly refreshed to preserve correspondence between IDs and the associated internal OMIDs.

STEP 2: Starting from the collection of citations expressed as directional links between identifiers of potentially any type (e.g., DOI-DOI, PMID-PMID, PMC-PMID, etc.), the INDEX software queries the internal database mapping IDs to OMIDs to produce an updated version of the OpenCitations Index: unique citations expressed as OMID-OMID links in different formats, accompanied by their corresponding provenance data.

Fig. 1: An overview of the data ingestion workflow, starting from the data source-specific conversion and production of citations and bibliographic metadata tables, progressing through the META process and the assignation of an OMID identifier to each bibliographic record involved in a citation, and culminating with the exposition of the OpenCitations Index collection of OMID-OMID unique citations.

What we have now: The OpenCitations Index

From now on, OpenCitations will no longer display an index of citation data for each source. Instead, we will publish a single collection of citations into which the contributions from each of the sources will flow, which we will simply call ‘The OpenCitations Index‘. The first version of this unified index of OMID-OMID citations is posted on Figshare. It was produced in RDF, CSV, and SCHOLIX formats, together with a collection of its provenance information, provided in RDF and CSV formats. For each citation, it is possible to trace the source of the information by consulting the Provenance data collection, thanks to the http://www.w3.org/ns/prov#atLocation property, which defines the location of each citation.

This new solution has the benefit of simplifying the consultation of the data maintained by our infrastructure without reducing the information content. In addition, by including efficient handling of the deduplication problem, the new Index not only provides accurate data on the exact number of unique citations exposed by the framework but also verifies the individual contribution of each source, as well as their overlapping data (Fig. 2).

Fig. 2: An overview of the number of citations stored in the OpenCitations Index as of October 31, 2023. The diagonal cells in the table (highlighted in yellow) show the unique contribution of each collection to the OpenCitations Index, while the other cells represent the citations that are shared between the collections. More in detail, the green cells show the overall input of each source, while the pink cells represent the number of overlapping citations between two data sources.

Currently, the Index contains almost 2 billion unique citations. By the end of November, a new version of the collection will be published, including the contribution of the new Japan Link Centre (JaLC) source.

How to access the OpenCitations Index data

To maximize the reuse of the exposed information and to ensure the greatest possible interoperability, the collection will always be published on Figshare in all formats listed above. In addition, the data will be accessible via an API, a SPARQL endpoint, and a web interface.

The redesign of the ingestion workflow marks a fundamental step for OpenCitations towards a more intuitive and simple access to our services while always preserving and improving the quality of our data. If you need further information on how the new workflow works, please visit our website, contact us at contact@opencitations.net or leave feedback and/or suggestions in the dedicated card on our public roadmap to help us improve our services and communications. Thank you!

OpenCitations needs you: support the change in research practices

In OpenCitations, we like to define our infrastructure organization as “community-based” and “community-driven”, and we really mean it. The support coming from the number of academic libraries and consortia coming after OpenCitations’ involvement in the 2nd SCOSS funding cycle has made it possible, starting from 2020, to make OpenCitations develop from a small university project based on time-limited grant incomes to being an open infrastructure globally recognized for the provision of open citation data and bibliographical metadata. We want to thank all our members and donors, for trusting our mission and sustaining OpenCitations activities with their continuous and generous support, despite the pandemic and post-pandemic times.

While retracing our work in the last three years, we are astonished by the achievements our team has accomplished, and by how in such a limited time frame OpenCitations has approached David Shotton’s initial vision (who is one of the co-directors of OpenCitations), when he first shaped the project back in 2010. Here are just some of the technical developments that have marked the last years:

in 2021, COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations crossed the threshold of one billion citations stored;
in 2022, we released the two new OpenCitations indexes of open citations, DOCI (citations from DataCite) and POCI (citations from PubMed);
we expanded our collection besides the citation data by releasing OpenCitations Meta, a database storing and delivering bibliographic metadata for all the publications in the OpenCitations Indexes, including the publication’s title, type, venue (e.g. journal name), volume number, issue number, page numbers, publication date, identifiers and details of the main actors involved in the document’s publication (the names of the authors, editors, and publishers);
as of October 2023, OpenCitations Indexes contain information on 1.82 billion unique open citations.

However, the most significant achievements for OpenCiations in the last years have been the creation of a prolific network of collaborations with other Open Science projects, such as OpenAIRE-Nexus, RISIS2 and GraspOS, and the establishment of a structured team, involving young researchers and PhD students, whose work at the University of Bologna has made it possible to work on the technical developments day by day.

Our results are a strong indicator of the growing sensibility on the theme of the open provision of bibliographical metadata and citation data, of which Open Citations is at the forefront as a founding member of the Initiative for Open Citations (I4OC) and the Initiative for Open Abstracts (I4OA). The effort and awareness campaigns led by these initiatives, by DORA and the Open Science community as a whole, have led more and more publishers to a change of heart and to open their reference lists. OpenCitations is an integral part of an ongoing process of transformation of the research environment, and we have collected and interpreted some of the needs of the academic community to plan our future activities and developments. We still need your help and support to make it possible to maintain and improve our infrastructure and to sustain the team working at OpenCitations.

If you believe in

the importance of open bibliographic data for the creation of reproducible metrics for research assessment exercises
the power of the scholarly community to change existing practice by reclaiming ownership of its own data– and you want to become an active part of this change

please consider supporting OpenCitations either via membership or donation. You can find all the information on membership on our website at https://opencitations.net/membership, or you can ask for information by contacting us at membership@opencitations.net.

Together, we can work to create an open and inclusive future for science and research.

Thank You!

The OpenCitations blog posts are now archived on Rogue Scholar with DOIs

Last April, Martin Fenner launched Rogue Scholar, an archive of science blogs aiming to index full-text of blog posts, establish a full-text search, and register DOIs and metadata for all posts. Rogue Scholar works with all blogging platforms that publish scholarly content and have an RSS or Atom feed with full-text content distributed under a Creative Commons Attribution (CC-BY 4.0) license.

Rogue Scholar currently features 40 blogs, including the OpenCitations blog, with more than 1,000 blog posts that are available via full-text search, with DOIs linking to the original post on one of 40 science blogs. By exploring the OpenCitations blog’s profile on Rogue Scholar, you will find the last 40 posts with summaries (derived from the information you get in the RSS feed), and by clicking on the DOI you will be redirected to the full post on the blog. The DOI metadata include abstract, language, license, and (OECD Fields of Science) subject category for all posts.

Rogue Scholar is growing day by day, and the increasing involvement of science blogs – from different disciplines and various languages – demonstrates that “a central archive of science blogs with full-text content, and DOIs for all blog posts with relevant metadata is feasible, making an important contribution to Open Scholarly infrastructure”.

Thanks to a recently launched Mastodon instance at Rogue Scholar Social, the OpenCitations blog has now its own Mastodon feed, where you can keep yourself updated about the last posts of the OpenCitations blog, by finding summaries and the related DOIs linking to the full post – and you can also boost and comment, of course! Please follow us at https://rogue-scholar.social/@opencitations to not miss anything.

If you are managing a Science Blog and are interested in adding it to the Rogue Scholar archive, or if you are just interested in the topic of metadata for scholarly blogs, please contact info@front-matter.io

OpenCitations is part of the CoARA Working Group Towards Open Infrastructures for Responsible Research Assessment (OI4RRA)

Last March, the  Coalition for Advancing Research Assessment (CoARA) launched its call for members to propose Working Groups and National Chapters. The aim of the call (which was closed in June) was to foster the creation of Working Groups that would work as ‘communities of practice’ to enable systemic reform of research assessment by providing mutual learning and collaboration on specific thematic areas.

A group of 23 Coalition members, including University of Bologna’s personnel working at OpenCitations, collaborated in designing and proposing the CoARA Working Group Towards Open Infrastructures for Responsible Research Assessment (OI4RRA), focusing on having open infrastructures for making research assessment more transparent and responsible, and thus enabling the research community to be in full control of the data and indicators it relies on in assessments.

We are now thrilled to announce that the proposed Working Group has been accepted, and will start its activities in the next months, with the mission to “enable institutions to move from proprietary infrastructure and research information, to open alternatives–in support of the transition to responsible research assessment practices. This effort will take into consideration the wide range of research outputs and open science practices and address the diversity of the global research community”.

The CoARA Working Group Towards Open Infrastructures for Responsible Research Assessment will work to facilitate the use of existing open infrastructures, -, with the aim to make it possible a transition to a fully OI4RRA ecosystem – interconnected, decentralised and open – that is fit to serve existing and emerging needs of reformed RRA agendas.

For more information visit the dedicated section on CoARA’s website, and read the full list of participants in OI4RRA here.

The Dutch Research Council sustains OpenCitations

We are most grateful to the Dutch Research Council (NWO) for its commitment to sustaining the activities and developments of three SCOSS-selected infrastructures (PKP, OpenCitations and ROR) together with the Netherlands Reproducibility Network.

The selected infrastructures have been evaluated as “essential for a high-quality open science communication system”, and part of a network that “helps to promote reproducibility and strengthens the transition to open science”. OpenCitations, in particular, plays a strong role in reducing “the reliance on commercial products for doing bibliometric research and citation measurement” by providing an open database of citations.

This pledge carries out NWO’s enhancement of Open Science policy, as part of its strategy 2023-2026. The Dutch Research Council aims to support and encourage projects that put Open Science into practice, thus contributing to the transition towards a healthier research culture.

The yearly funding of 8000 EUR (year 2023-2025) will help us realise our planned future developments. Thank you, NWO!