Discover POCI, the index of open citations from PubMed 

We’re happy to announce POCI, the OpenCitations Index of PubMed open PMID-to-PMID citations, an RDF dataset containing details of all the citations from publications bearing PubMed Identifiers (PMIDs) to other PMID-identified publications, harvested from the National Institutes of Health Open Citations Collection (NIH-OCC). The citations available in POCI are treated as first-class data entities, with accompanying properties including the citations timespan, modelled according to the OpenCitations Data Model. 

Currently, POCI’s December 2022 release contains 717,654,703 citations from 26,024,862 bibliographic resources, and is based on the dump of NIH Open Citation Collection dated November 2022. 

Citation URLs

Each citation (i.e. an individual of the class cito:Citation) is identified by an URL structured as follows:

https://w3id.org/oc/index/poci/ci/[[OCI]].

Open Citation Identifiers

Each Open Citation Identifier [[OCI]] has a simple structure: the lower-case letters “oci” followed by a colon, followed by two numbers separated by a dash (e.g. https://w3id.org/oc/index/poci/ci/01600102060800080706-016002060909030401), in which the first number identifies the citing work and the second number identifies the cited work.

For citations in which the citing and cited works are identified by PMIDs, which includes all the POCI citations, the OCI is created in the following manner, as explained more fully here. Each converted numeral part of OCI is prefixed by a 0160, which indicates that NIH is the supplier of the original metadata of the citation (as indicated at http://opencitations.net/oci).

OCIs can be resolved using the OpenCitations OCI Resolution Service.

Access to POCI data

All the data in POCI:

What is an Open Citation Index?

A citation index is a bibliographic index recording citations between publications, allowing the user to establish which later documents cite earlier documents. The current indexes available in OpenCitations are:  

All the OpenCitations Indexes have six characteristics in common, summarized here: https://opencitations.net/index   

 

Discover DOCI, the index of open citations from DataCite

We’re excited to introduce DOCI, the OpenCitations Index of Datacite open DOI-to-DOI citations, a new tool containing citations derived from publications bearing DataCite DOIs to other DOI-identified publications, harvested from DataCite. The citations available in DOCI are treated as first-class data entities, with accompanying properties including the citations timespan, modelled according to the OpenCitations Data Model

Currently, DOCI’s December 2022 release contains 169,822,752 citations from 1,753,860  citing resources, and is based on the last dump of DataCite dated 22 October 2021 provided by the Internet Archive

Citation URLs

Each citation (i.e. an individual of the class cito:Citation) is identified by an URL structured as follows:

 https://w3id.org/oc/index/doci/ci/[[OCI]].

Open Citation Identifiers

Each Open Citation Identifier [[OCI]] has a simple structure: the lower-case letters “oci” followed by a colon, followed by two numbers separated by a dash (e.g. https://opencitations.net/index/doci/ci/080010504060836132137200707121027-080010504060836161221130313.html), in which the first number identifies the citing work and the second number identifies the cited work.

For citations in which the citing and cited works are identified by DOIs, which includes all the DOCI citations, the OCI is created in the following manner, as explained more fully here. Each case-insensitive DOI is first normalized to lower case letters. Then, after omitting the initial doi:10. prefix, the alphanumeric string of the DOI is converted reversibly to a pure numerical string using the simple two-numeral lookup table for numerals, lower case letters and other characters presented at https://github.com/opencitations/oci/blob/master/lookup.csv. Finally, each converted numeral is prefixes by a 080, which indicates that DataCite is the supplier of the original metadata of the citation (as indicated at http://opencitations.net/oci).

OCIs can be resolved using the OpenCitations OCI Resolution Service.

Access to DOCI data

All the data in DOCI:

More information is available at https://opencitations.net/index/doci. 

What is an Open Citation Index? 

A citation index is a bibliographic index recording citations between publications, allowing the user to establish which later documents cite earlier documents. The current indexes available in OpenCitations are: 

All the OpenCitations Indexes have six characteristics in common, summarized here: https://opencitations.net/index  

Follow OpenCitations on Mastodon

OpenCitations has happily joined the open-source social media platform joinmastodon.org.

Mastodon is “a free and open-source software developed by a non-profit organization”, with the aim of favouring interoperability and bringing social media interaction “back in the hands of the people”.

We look forward to recreating there our wide network of connections, and getting in touch with new people, projects and institutions in a different virtual environment.

Follow us at https://scicomm.xyz/@opencitations !

OpenCitations Access Tokens: how they work and why they are important

Since its inauguration in 2010, OpenCitations has always granted free access to its services to users throughout the world, with no requirement for registration or sign-up. Programmatic access to OpenCitations data can be obtained either via our SPARQL endpoints and our REST APIs. In addition, OpenCitations data – available in CSV, Scholix, and RDF formats – can be downloaded from data dumps made periodically and stored on Figshare, so as to enable large-scale analyses using the whole content of the data sets, and also be obtained via our user-friendly text-based search and browsing interfaces.

One of OpenCitations’ priorities is (and will always be) to keep its data globally open and available at zero cost and without restriction for third-party analysis and re-use. As a matter of sustainability, OpenCitations relies on financial support from the scholarly community, which includes those institutions that use OpenCitations data. However, OpenCitations has not so far had in place a proper system to monitor its users, and the main evidence of the impact of OpenCitations in different academic fields and countries has been incompletely obtained from direct contacts with our members and donors across the world, our collaborations with international projects, and the interactions on our social platforms (Twitter and LinkedIn).

We would now like to institute a system that enables us to follow the usage and assess the impact of OpenCitations more reliably. For this purpose, we are now happy to announce the launch of the OpenCitations Access Token System for access to the OpenCitations data and services.

An OpenCitations Access Token is an opaque character string that anonymously identifies a unique user of the OpenCitations APIs. OpenCitations assigns an access token only if authorized to do so by each user, who can request a token by inserting his/her email address into the access form and clicking “Get token”. Upon submission of such a request, each user will automatically receive a personal access token by email. Users can save their personal access token and reuse it every time calling the APIs of OpenCitations, by passing it as a value for the key access-token in the header of each API call. 

Obtaining and using an OpenCitations Access Token is thus easy. It only requires a simple form request, and then the insertion of your personal token into the API call header when using OpenCitations REST APIs. OpenCitations will not store users’ email addresses or any personal information, so that the users’ privacy will be totally safeguarded. The token system just provides a simple mechanism for identifying unique users, for which the use of IP addresses is insufficient.

Obtaining an OpenCitations Access Token will take the user only a few seconds and needs to happen only once. You can request your OpenCitations Access Token here

https://opencitations.net/accesstoken 

Use of an OpenCitations Access Token is not compulsory. However, token use will help OpenCitations incredibly, by enabling us to monitor the number of the unique users accessing our data and services, providing objective anonymized evidence of the number of institutions and researchers accessing our data either occasionally or on a regular basis, which we can then employ to demonstrate the usefulness of OpenCitations in the research environment. While the token system will initially be employed just for API calls (the most used service we offer), it will subsequently be extended to our other forms of data access.

OpenCitations exists for the people that use its data for research purposes every day, and thanks to their support. This is why obtaining precise knowledge of how many researchers and institutions are accessing our services is essential to us, since it will enable us to present the uniqueness and value of OpenCitations to new communities of stakeholders, and thus to make it possible to enlarge the already enthusiastic and diverse group of people and institutions supporting and using our Open Science Infrastructure.

To summarize: Getting and using an OpenCitations Access Token is voluntary, easy, and does not cost you anything. However, it will help OpenCitations a great deal. Please get your own token now, and use it next time you access OpenCitations. Thank you very much!

 

Additional 48 million citations in COCI, including references from IEEE 

We announce the August 2022 release of COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations, which is based on open references to works with DOIs within the Crossref dump dated August 2022. This new release extends COCI with more than 48 million additional citations, giving a total number of more than 1.36 billion DOI-to-DOI citation links. 

This release includes citations from the articles published over the last four years by IEEE, whose bibliographic references were opened in June 2022. 

A fundamental role in pushing the commercial publishers to open their citation data was played by Crossref’s recent announcement to change its reference distribution policy, by making all its metadata open.  

Besides IEEE, COCI already includes the citation data derived from Elsevier (open via Crossref since December 2020) and from the last articles published by the American Chemical Society (whose references were opened in February 2021) 

You can find more information about COCI in our open-access article  

Ivan Heibi, Silvio Peroni & David Shotton (2019). Software review: COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations. Scientometrics, 121 (2): 1213-1228. DOI: https://doi.org/10.1007/s11192-019-03217-6    

Finally, just a reminder that the bibliographic and citation data in COCI:  

    • can be queried using the OpenCitations Indexes SPARQL endpoint;  
    • can be retrieved by using the COCI REST API;  
    • can be searched by using the OpenCitations Indexes Search Interface;  
    • are also available as dumps on Figshare in CSV, N-Triples, and Scholix; and  
    • can be freely re-used for any purpose.

New documents that present OpenCitations’ mission, unique benefits, present status and future plans

Posted on August 10th 2022 by Chiara Di Giambattista

More than a year ago, Ginny Hendricks, Director of Member & Community Outreach for Crossref, and a valued member of the OpenCitations International Advisory Board, published on the Crossref blog the post “The road ahead: our strategy through 2025”. In order to describe all Crossref’s principles and activities, Ginny presented the Crossref strategic planning framework as a diagram summarizing Crossref’s statements, key messages and truths. The clarity and immediacy of the diagram were such that we adapted it to present  OpenCitations’ own statements and goals. The resulting poster “OpenCitations – what does the future hold?” was presented by our Director David Shotton at the OASPA2021 conference, and can be found in this blog post.

Although the poster offered a wide overview of OpenCitations values, unique traits, benefits and plans, it differed slightly from Ginny’s original diagram, in particular because it lacked a “Mission Statement”, scattering the relevant information within the “Values” and “Principles” boxes. Indeed, at that time (September 2021), we didn’t have a clearly defined Mission Statement.

Nevertheless, the creation of that poster was crucial in helping us start to articulate more clearly the purpose and meaning of OpenCitations. As David underlined in his post “From little acorns…a retrospective on OpenCitations”, since 2018 OpenCitations activities have progressively increased and, with them, the number of related journal articles, conference papers and technical definitions. OpenCitations’ involvement in international networks and collaborations (such as SCOSS and the OpenAIRE-Nexus project), together with our need of identifying and reaching out to new stakeholders to assure OpenCitations’ development and sustainability, has made it necessary to publicly define OpenCitations’ mission, unique strengths and next developmental steps.

After numerous revisions, aided by wise advice from members of the OpenCitations Advisory Board members, we’re now happy to publish the following three OpenCitations documents:

OpenCitations Mission Statement,

The Uniqueness of OpenCitations   and

OpenCitations – Present Status and Future Plans,

which together provide a summary of why we exist and where we are heading.

We are particularly proud of the definition of OpenCitations’ primary mission, namely

to harvest and openly publish accurate and comprehensive metadata describing the world’s academic publications and the scholarly citations that link them, and to preserve ongoing access to this information by secure archiving.

The Mission Statement also presents brief descriptions of the OpenCitations context, our vision, our value proposition and our relationship with the community and stakeholders.

The Uniqueness of OpenCitations provides the answer to the question ‘Why choose to use OpenCitations?’, and is a detailed presentation of OpenCitations’ benefits.

OpenCitations – Present Status and Future Plans summarizes OpenCitations’ ongoing activities, that can be quickly visualized on our public roadmap. It also introduces the OpenCitations Working Groups, served by the members of the OpenCitations International Advisory Board, which are currently working on the themes of governance evolution and community building, with the common purpose of driving OpenCitations along the path from being a ‘sustainable infrastructure’ (in POSI terms) to being an enduring community led and financially sustained infrastructure.

In fulfilling our mission and reaching our goals, the support and vital interest of our community members is fundamental. We request that you, as a member of our community, provide us with feedback on these documents and the ideas they contain, or indeed to ask for clarifications, to help us improving our mission and our communications to explain it. You can reach us here: contact@opencitations.net.

Thank you!

Two years of achievements within the ‘SCOSS family’ (and it’s not over yet!) 

Posted on August 10th 2022 by Chiara Di Giambattista

← Previous post: The OpenCitations Roadmap is now publicly available on Trello

→ Next post: New documents that present OpenCitations’ mission, unique benefits, present status and future plans

In March, The Global Sustainability Coalition for Open Science Services (SCOSS) celebrated, together with the generous funders and the projects involved (including OpenCitations), the achievement of an amazing milestone: a total of 4 million Euros raised so far for supporting the growth and development of Open Science Infrastructures. This significant sum is not just a number, but a concrete sign of the commitment of numerous institutions all over the world to ensure the success of vital organs of the Open Science ecosystem. Thanks to the pledges recently made, the new infrastructures selected for the third SCOSS pledging round have now started developing their services and can now look to the future with more surety.   

At the end of 2019, OpenCitations was selected by SCOSS for its second pledging round, and since then much progress has been made. As the OpenCitations’ founder and director David Shotton recently stated: 

“OpenCitations is growing, thanks to the generous support from our members and donors, and we thank SCOSS sincerely for bringing us into contact with them. The citation coverage provided by OpenCitations is now approaching parity with that of the leading commercial citation indexes, and our ambition, within the next five years, is for OpenCitations to be routinely used by our worldwide stakeholders as their primary source of comprehensive scholarly citation information”.   

In 2020, OpenCitations monitored the achievements of the first year of SCOSS support and shared the most important updates in a blog post. After a review from SCOSS Advisory Group and the SCOSS Board, the OpenCitations 2021 report to SCOSS is now available in the SCOSS May newsletter. We’re proud of the successful developments that 2021 brought with it in many areas, from the technical enhancements to OpenCitations to its new supporters and partnerships.   

After a two-year-long collaboration, we in OpenCitations recognise that one of the most precious benefits of being part of SCOSS is working within a community: SCOSS not only provides a framework but also a real family of supportive institutions that support the Infrastructures during their growth and provide a safety net if troubles occur along the path. The bi-monthly meetings organized by the SCOSS team enable dialogue with the other infrastructures within the same pledging round, while presentation and promotion to the institutions worldwide are fostered by participation in webinars and conferences. During  2021, OpenCitations participated in 16 events, and in 5 of them (LIBER Webinar 2021, JISC Webinar 2021, LIBER Annual Conference 2021, Open Science Fair 2021, and Open Access Tage 2021) OpenCitations’ director Silvio Peroni gave talks together with the representatives of others infrastructures involved in the SCOSS second pledging round.   

In compliance with the POSI principles, SCOSS encouraged OpenCitations to set up an open governance structure. As described here, the organizational bodies included in the OpenCitations present governance are three: the Directors, the International Advisory Board, and the Council. Although executive power is still currently vested in the hands of the Directors, in the last two years the OpenCitations International Advisory Board, a committee that now comprises nine Open Science experts from different professional and academic backgrounds, has had a crucial role in guiding the OpenCitations activities, and it is now working on strategic developments in terms of collaborations, policies, support and governance. Moreover, last December OpenCitations organized a Webinar in conjunction with its Annual Meeting to present and discuss with the OpenCitations Council members OpenCitations’ recent developments and future plans.   

OpenCitations is highly reliant upon the connections we have created and on people working together: thanks to the support we received throughout the last two years, the OpenCitations team has grown and now includes six people employed by the Research Centre for Open Scholarly Metadata at the University of Bologna, the administrative body for OpenCitations. Besides the previously announced appointments of Claudio Fabbri (Research Manager), Chiara Di Giambattista (Communications Director and Community Development Manager), Giuseppe Grieco (Software and Systems Developer), and Arcangelo Massari (Software Developer, working within the OpenAIRE-Nexus project), early in 2022 Ivan Heibi, Ph.D. candidate at the University of Bologna, joined OpenCitations with responsibility for the technical infrastructure, and Arianna Moretti, who recently graduated in Digital Humanities and Digital Knowledge, joined as a software developer. This enlarged team, involving young and motivated researchers, is working on numerous projects to be announced later in 2022. You can learn more about OpenCitations’ ongoing activities on our public roadmap.   

OpenCitations’ aim continues to be the publication of open data describing the bibliographic citations linking global scholarly publications, with depth and scope, while maintaining the highest standards of accuracy and provenance. Most importantly, OpenCitations services will always be free, making global scholarly citation data available at zero cost and without restriction for third party analysis and re-use. 

With its support, SCOSS has been helping OpenCitations to pursue its mission and spread the benefits of Open Science. However, 2022 will be the last year of the three-year-long support ensured by SCOSS. OpenCitations activities won’t stop in 2023 — indeed there still are many long-planned activities that we hope to initiate in the near future, given sufficient resources. This is why OpenCitations requires ongoing support from the scholarly community. All the information you may require to start helping us financially is available on the OpenCitations website:  https://opencitations.net/membership 

By supporting OpenCitations, you will embrace and sustain the ideals and vision of Open Science, and you will help in creating a more open, democratic and fair knowledge environment.   

The OpenCitations Roadmap is now publicly available on Trello

Want to keep yourself updated about the ongoing activities of OpenCitations? We have now publicly released the OpenCitations Roadmap, available on Trello.com:

https://trello.com/b/RprHYoKL/opencitations

The OpenCitations Roadmap consists of a board fulfilled with colour-labelled cards which present the goals so far reached, the present projects and activities, and the future plans. By clicking on the cards, it is possible to visualize a description for each activity, the progress state, and who in the OpenCitations team is working on it.

The OpenCitations Roadmap covers all kinds of activities divided according to the scope, identified by the coloured labels, in particular:

  • light blue for the technical development, such as the development of the software for the creation of the new database OpenCitations Meta and of DOCI, the OpenCitations Index of DataCite open DOI-to-DOI citations, and the re-engineering of the infrastructure and the website;
  • green for the data model implementation;
  • yellow for the data development, such as the bi-monthly COCI releases;
  • purple for the events and outreach activities.

The cards also highlight the activities related to the two EC-funded projects OpenCitations is involved in, OpenAIRE Nexus (blue label) and RISIS2 (orange label). We thank the OpenAIRE team for the help and suggestions during the Roadmap review process.

The OpenCitations Roadmap is an open work in progress that will reflect the developments and growth of OpenCitations. At OpenCitations, we don’t want this Roadmap to be just an online ‘showcase’, but a room in which to share ideas and opinions. We invite you – the members of our community, our stakeholders, the other Open Science actors, researchers, and librarians, and anyone who is interested in OpenCitations activities – to add a comment or a question in the ‘Leave feedback‘ card. This will help us to better understand our strong and weak points, and to stay in touch with the needs and thoughts of the community.

In this way, supplementing the conventional communications channels of email and the social platforms (our blog, Twitter, LinkedIn), the OpenCitations Roadmap will become a new virtual place for dialogue, where you can directly contribute to improve OpenCitations.

OpenCitations and EC funding: OpenAIRE Nexus and RISIS2

The incentives for new OpenCitations innovative solutions

Two years ago, in their canonical 2020 QSS paper on OpenCitations, Silvio Peroni and David Shotton anticipated the creation of the new database, OpenCitations Meta, able to “offer a faster and richer service” by storing bibliographic metadata “in house”. Meta would “avoid duplication of data by efficiently permitting us to keep […] a single copy of the metadata for each of the bibliographic entities involved as citing or cited entities in the different OpenCitations’ citation indexes”, would remove the requirement for potentially slow API calls to external metadata sources such as Crossref and ORCID, and would enable us to index citations involving entities lacking DOIs.

Important synergies to achieve goals

Today, thanks to the recent involvement of OpenCitations in two EC-funded projects, the OpenAIRE-Nexus Project (Horizon 2020 EU funded project, GA: 101017452) and the RISIS2 Project (Horizon 2020 EU funded project, GA: 824091), the development of OpenCitations Meta has commenced, with a planned release date later in 2022.

The OpenAIRE-Nexus project started in January 2021 to embrace and expand the operation of a portfolio of thirteen services, provided by OpenAIRE infrastructure, public institutions, organisations and universities, classified into three portfolios entitled PUBLISH, MONITOR, and DISCOVER. The OpenAIRE-Nexus portfolios focus on the demands of the three main categories of the research lifecycle.  Therefore, OpenAIRE-Nexus makes sure such services are integrated to provide a uniform Open Science Scholarly Communication package for the European Open Science Cloud (EOSC). Within the OpenAIRE Nexus project there is scope for producing not only support materials (factsheet, guides, video tutorials, demos) but also training sessions where the services in the three portfolios will be showcased, anticipating the EOSC onboarding process. The role of OpenCitations in the project is to provide open bibliographic citations, and interconnect and integrate (and vice versa) functionalities with the  OpenAIRE Research Graph and more OpenAIRE-Nexus services such as EpiSciences, OpenAIRE MONITOR) the core component of OpenAIRE infrastructure and services and of the EOSC Resource Catalogue. 

Additionally, we are happy to announce our recent involvement in the RISIS2 Project. The Research Infrastructure for Science and Innovation Policy Studies (RISIS) is a project funded by the European Union under a Horizon2020 Research and Innovation Programme. RISIS2 involves 18 partners working together to create and maintain a research infrastructure for the field of Science, Technology, and Industry (STI) Studies, and to build an advanced research community in this field. OpenCitations’ contributions to RISIS2 will include not only the creation of OpenCitations Meta but also the development of a new citation index of open references, the OpenCitations Index of DataCite Open Citations (DOCI), which will be based on the open reference holdings of DataCite and, together with COCI, will be cross-searchable through our unified OpenCitations API.

Lessons learnt so far

A year into the OpenAIRE-Nexus project, we have found that one of the most significant benefits for OpenCitations is our involvement with this wide cooperative network of European research infrastructures, services, and communities, within which we can exchange experiences, ideas, and knowledge, and discuss any challenges and outcomes with our colleagues. More importantly, OpenCitations becomes positioned within the Open Science ecosystem, as a valuable innovative infrastructure with strong proof of integration and interoperable operations. Being part of the OpenAIRE-Nexus team has opened up more future challenges and expectations, and raised the bar for the inclusion of more functionalities of value. Thanks to the dedication of its efficient communication team, OpenAIRE is also helping us by communicating OpenCitations services to additional users and stakeholders, by inclusion within the comprehensive OpenAIRE services catalogue, by releasing an OpenCitations factsheet and by permitting us to present the latest information on OpenCitations through established events (i.e. Open Science FAIR 2022). FAIR and openness of information is our motto, and we strongly promote this through all our activities.

Expanding our team

As announced in our previous blog post “Five reasons why 2021 has been a great year for OpenCitations”, the support we receive from the EU as part of OpenAIRE-Nexus has enabled our recent appointment of Arcangelo Massari, a software developer who is now playing a crucial role in the creation and development of OpenCitations Meta.

As the year 2022 progresses, we look forward to bringing you further information about other new goals for OpenCitations, made possible by the support we receive from our numerous partnerships.

Search OpenEdition Search

You will be redirected to OpenEdition Search