Open scholarship – Page 4 – OpenCitations blog

OpenCitations described

OpenCitations is an infrastructure organization for open scholarship dedicated to the publication of open bibliographic and citation data. We at OpenCitations are proud to announce the publication, in the first issue of Quantitative Science Studies, of a canonical paper in which we introduce and describe OpenCitations and outline its achievements and goals [1].

Here, I outline the contents of our paper, and provide definitive links on the topics described. Many of these topics have been the subjects of earlier blog posts.

This paper appears in the first Special Issue of QSS, dedicated to the description of the bibliometric data sources that lie at the heart of scientometric research, which aims to characterize the most important data sources currently available and to show how they differ in various dimensions, for instance in the data they provide, their level of openness, and their support for making research reproducible. The first three papers in this special issue cover the most important commercial bibliographic data sources: Web of Science (Clarivate Analytics), Scopus (Elsevier), and Dimensions (Digital Science), while the remaining three articles describe open data sources: Microsoft Academic, Crossref and OpenCitations.

In the introduction to our own paper, we describe the origins of OpenCitations, discuss the growth and benefits of open science, and introduce the Semantic Web techniques used at OpenCitations for recording and publishing our data. We then go on to describe OpenCitations’ services and data, namely Open Citation Identifiers, the OpenCitations Data Model, the SPAR (Semantic Publishing and Referencing) Ontologies, the OpenCitations Corpus, and the OpenCitations Indexes of citation data, of which the first and largest is COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations, that currently holds information on over 624 million citations. We conclude our survey of OpenCitations’ services and data by outlining the generic open source software developed at OpenCitations, including OSCAR, the OpenCitations RDF Search Application for searching over RDF datasets, LUCINDA, OSCAR’s associated OpenCitations RDF Resource Browser, and RAMOSE, OpenCitations’ application for creating REST APIs over SPARQL endpoints, thus opening Semantic Web datasets to those not familiar with SPARQL, the RDF query language.

In the second half of the paper, we describe OpenCitations as an organization in terms of its compliance with the principles for the sustainability of open infrastructures proposed by Bilder, Lin and Neylon (2015) [2], and report the selection of OpenCitations by the Global Sustainability Coalition for Open Science Services (SCOSS) as an open infrastructure organization worthy of crowd-funding support by the stakeholder community. We then provide usage statistics for our datasets and web site, and describe the adoption of OpenCitations data and services by the community, before concluding with a forward look at our proposed developments of OpenCitations activities.

References

[1] Silvio Peroni and David Shotton (2020). OpenCitations, an infrastructure organization for open scholarship. Quantitative Science Studies 1 (1): 428-444. https://doi.org/10.1162/qss_a_00023

[2] Geoffrey Bilder, Jennifer Lin and Cameron Neylon (2015). Principles for open scholarly infrastructures. Figshare. https://doi.org/10.6084/m9.figshare.1314859

The first issue of Quantitative Science Studies

The memorable date 20/02/2020 saw the publication by MIT Press of the first issue of Volume One of a new journal, Quantitative Science Studies (QSS), the official open access journal of the International Society for Scientometrics and Informetrics (ISSI). QSS’s Editor in Chief is Ludo Waltman (CWTS, University of Leiden, Netherlands), Vincent Larivière (Université de Montréal, Montreal, Quebec, Canada) and Staša Milojević (Indiana University Bloomington, Bloomington, Indiana, USA) are its Associate Editors, and it has a large and distinguished editorial board.

What makes the launch of this new journal remarkable is the story of how it came into being. In 2019, the entire editorial team of the Journal of Informetrics (JOI), a leading journal in this field published by Elsevier, resigned en masse and decided to start an alternative journal, QSS, both because of Elsevier’s position on open citations, and because, in their opinion, the financial model used by Elsevier violates the scientific ethos.

Reproducibility in the field of scientometrics requires scientific metadata that are both of high-quality and open, particularly those relating to bibliographic citations. The JOI editorial board was deeply concerned by the refusal of Elsevier to join almost all other large scholarly publishers in supporting the Initiative for Open Citations (I4OC). As we have previously reported on this blog, Elsevier is the largest contributor of bibliographic references to Crossref, but insists that these data should be kept closed.

Elsevier’s position, driven by commercial interests (since it sells access to citation data through Scopus), flies in the face of the scientific community’s clear move towards open science, with hundreds of scientometricians having signed an ISSI open letter urging scholarly publishers to support I4OC.

Science is a self-governing system, and the editorial team held the view that the ultimate responsibility for a scholarly journal should fall with the scientific community, who serve as the gatekeepers, producers, and consumers of scientific content.

The editorial team also believed Elsevier’s subscription fees to be excessive, and its article processing charges (APCs) for open access publishing to be unfairly high, thus limiting both those who can afford to read Elsevier journals and those who can afford to publish in them, so that publishing with Elsevier inevitably places major limits on scholarship, harming both science and society. It was for all these reasons that they forsook JOI and started QSS.

We at OpenCitations congratulate the editorial team for their courage in deciding to make this journal flip, and wish them, together with the ISSI and MIT Press, every success for this important new journal. We also commend the Technische Informationsbibliothek (TIB) – Leibniz Information Centre for Science and Technology and the Communication, Information, Media Centre (KIM) of the University of Konstanz, who, in collaboration with the Fair Open Access Alliance (FOAA), have generously agreed to cover APCs for the first three years of the QSS journal.

OpenCitations selected for SCOSS second funding cycle

The Global Sustainability Coalition for Open Science Services (SCOSS) is launching its second funding cycle, and OpenCitations is one of three open science infrastructure organizations whose services have been evaluated and selected for presentation to the international scholarly community for crowd-sourced sustainability funding, along with the Public Knowledge Project (PKP) and the Directory of Open Access Books (DOAB).

OpenCitations is an innovative infrastructure organization for open scholarship dedicated to the publication of open bibliographic and citation data concerning academic publications as Linked Open Data using Semantic Web technologies, thereby providing a disruptive alternative to traditional proprietary citation indexes. It also undertakes related advocacy work, particularly as a founding member of the Initiative for Open Citations (I4OC).

OpenCitations developed the OpenCitations Corpus (OCC), a database of open downloadable bibliographic and citation data recorded in RDF and released under a Creative Commons CC0 public domain waiver, which currently contains information about 14 million citation links to over 7.5 million cited resources. In addition and separately, OpenCitations is currently developing a number of Open Citation Indexes, using the data openly available in third-party bibliographic databases. The first and largest of these is COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations, which presently contains information encoded in RDF on more than 445 million citations, released under a CC0 waiver.

OpenCitations structures its data according to the OpenCitations Data Model (OCDM), that may also be employed by third parties, either for their own use or to structure their data for submission to and publication by OpenCitations. This model uses OpenCitations’ suite of SPAR (Semantic Publishing and Referencing) Ontologies developed to describe all aspects of the scholarly publishing domain. OpenCitations has also published open software of generic applicability for searching, browsing and providing REST APIs over RDF triplestores.

OpenCitations fully supports the founding principles of Open Science. It complies with the FAIR data principles proposed by Force11 that data should be findable, accessible, interoperable and re-usable, and it complies with the recommendations of I4OC that citation data, in particular, should be structured, separable and open. OpenCitations has published a formal definition of an open citation, and has launched a system for globally unique and persistent identifiers (PIDs) for bibliographic citations – the Open Citation Identifiers (OCIs) – for which it maintains an OCI resolution service.

OpenCitations has the potential to be a game-changer in the scholarly information landscape, giving institutions and individuals the ability to analyse and reuse publication citations in other infrastructures, in library collections, and in research. Open citation data are particularly valuable for bibliometric analysis, increasing the reproducibility of large-scale analyses by enabling the publication of the source data upon which analytical results are based. Since citation data are also crucial to evaluating research performance, such access to open, transparent citation data sources is a priority for Open Science.

SCOSS was formed in early 2017 with the purpose of providing a new coordinated and targeted crowd-sourcing and cost-sharing framework to enable the Open Access and Open Science communities to support the open infrastructure services on which they depend. In its first funding cycle, more than 1.5 million euros was pledged by more than 200 institutions worldwide to help fund and sustain the Directory of Open Access Journals (DOAJ) and SHERPA/RoMEO.

With the launch of its second funding cycle, SCOSS is appealing to academic institutions and their libraries, research institutes, publishers, funding organisations, national and regional governments, international organisations, learned societies and service providers worldwide — everyone who is invested in Open Access and Open Science — to support one or more of these three new selected open infrastructure services through a three-year commitment.

For more details about the services, suggested funding levels, and how you can help support OpenCitations, please see https://sparceurope.org/download/7913/ or contact us at donations@opencitations.net.

Workshop on Open Citations

OpenCitations [1], the EXCITE Project [2] and Europe PubMed Central [3] are pleased to announce a Workshop on Open Citations at the University of Bologna in Bologna, Italy [4] on 3-5 September – https://workshop-oc.github.io.

Format and topics

Day One and Day Two: Formal presentations and discussions on the creation, availability, uses and applications of open bibliographic citations, and of bibliometric studies based upon them. This will involve both invited and contributed presentations.
Day Three: A Hack Day on Open Citations to see what services can be prototyped using large volumes of open citation data.

We look forward to welcoming all those interested in open citation data, including researchers, computer scientists, scholarly publishers, academic administrators, research funders and policy makers. The workshop will be organised around the following topics:

Opening up citations: Initiatives, collaborations, methods and approaches for the creation of open access to bibliographic citations.
Policies and funding: Strategies, policies and mandates for promoting open access to citations, and transparency and reproducibility of research and research evaluation.
Publishers and learned societies: Approaches to, benefits of, and issues surrounding the deposit, distribution, and services for open bibliographic metadata and citations.
Projects: Metrics, visualizations and other projects. The uses and applications of open citations, and bibliometric analyses and metrics based upon them

Participation

If you would like to participate in this event, please enter your details and a mini-biography at https://bit.ly/2JEd0r9.

If additionally you would like to speak at this event, please select the session your talk would fit in, and provide a title and abstract for your talk. Selected submissions will involve either a talk of 10 minute duration, with a 5 minute discussion following, or a poster presentation.

The deadline for application and submission of these details is the 20th of May 2018. Notifications of acceptance will be sent to you by the 1st of June. In case of oversubscriptions, the organisers will select speakers and attendees from among those have applied.

Please circulate this invitation to any colleagues that you think might be interested in attending this workshop.

Fees and expenses

For those accepted, we request a small registration fee of €100 to cover expenses (€25 for students), which must be paid by the 15th of July 2018, but which will be waived in cases of financial hardship. Details of how to pay will be sent to those accepted. Registration for the Hack Day is free of charge.

Those attending will be expected to cover the cost of their own travel and accommodation. We will provide a list of recommended hotels and guest houses. We will provide lunches and refreshments on all days, and a free workshop dinner on Monday 3rd September.

Organizers

David Shotton (OpenCitations)
Jo McEntyre (Europe PMC)
Maria Levchenko (Europe PMC)
Marilena Daquino (University of Bologna)
Philipp Mayr (EXCITE project)
Silvio Peroni (OpenCitations)
Steffen Staab (EXCITE project)

Links

[1] OpenCitations – http://opencitations.net
[2] EXCITE Project – http://west.uni-koblenz.de/en/research/excite
[3] Europe PMC – https://europepmc.org/About
[4] University of Bologna – http://www.unibo.it/en/homepage

Early adopters of the OpenCitations Data Model

OpenCitations is very pleased to announce its collaboration with four new scholarly Research and Development projects that are early adopters of the recently updated OpenCitations Data Model, described in this blog post.

The four projects are similar, in that they each are independently using text mining and optical character recognition or PDF extraction techniques to extract citation information from the reference lists of published works, and are making these citations available as Linked Open Data. Three of the four will also use the OpenCitations Corpus as publication platform for their citation data. The academic disciplines from which these citation data are being extracted are social science, humanities and economics.

1 Linked Open Citation Database (LOC-DB)

The Linked Open Citation Database, with partners in Mannheim, Stuttgart, Kiel, and Kaiserslautern (LOC-DB, https://locdb.bib.uni-mannheim.de/blog/en/), is the first of two German projects funded by the Deutsche Forschungsgemeinschaft (DFG) that are extracting citations from Social Science publications. Dr. Annette Klein, Deputy Director of the Mannheim University Library, is the project manager.

The project is using Deep Neural Networks based approaches for reference detection and state-of-the-art methods for information extraction and semantic labelling of reference lists from electronic and print media with arbitrary layouts [3]. The raw data obtained will be manually checked against and linked with existing bibliographic metadata sources in an editorial system. They will then be structured in RDF using the OpenCitations Data Model, and published in the Linked Open Citations Database under a CC0 waiver. Using its libraries’ own Social Science print holdings and licensed electronic journals as subject material, this project will demonstrate how these citation extraction processes can be applied to the holdings of individual academic libraries, and can be integrated with library catalogues [1, 2, 3].

References

[1] Kai Eckert, Anne Lauscher and Akansha Bhardwaj (2017) LOC-DB: A Linked Open Citation Database provided by Libraries. Motivation and Challenges. EXCITE Workshop 2017: “Challenges in Extracting and Managing References”. https://locdb.bib.uni-mannheim.de/wordpress/wp-content/uploads/2016/11/LOC-DB@EXCITE.pdf

[2] Lauscher, Anne; Eckert, Kai; Galke, Lukas; Scherp, Ansgar; Rizvi, Syed Tahseen Raza; Ahmed, Sheraz; Dengel, Andreas; Zumstein, Philipp; Klein, Annette (2018) Linked Open Citation Database: Enabling libraries to contribute to an open and interconnected citation graph. Accepted for the JCDL 2018: Joint Conference on Digital Libraries 2018, June 3-6, 2018 in Fort Worth, Texas [Preprint of the conference publication].
https://locdb.bib.uni-mannheim.de/wordpress/wp-content/uploads/2018/04/LOCDB-JCDL2018-paper-camera-ready.pdf

[3] Bhardwaj A., Mercier D., Dengel A., Ahmed S. (2017). DeepBIBX: deep learning for image based bibliographic data extraction. In: Liu D., Xie S., Li Y., Zhao D., El-Alfy ES. (eds) Neural Information Processing. ICONIP 2017. Lecture Notes in Computer Science, vol 10635. Springer, Cham [Conference publication].

2 The EXCITE (Extraction of Citations from PDF Documents) Project

The EXCITE Project (http://west.uni-koblenz.de/en/research/excite/), run jointly at the University of Koblenz-Landau and GESIS (Leibniz Institute for Social Sciences), is the second project funded by the Deutsche Forschungsgemeinschaft (DFG) that is extracting citations from Social Science publications. It is headed by Steffen Staab, head of the Institute for Web Science and Technologies at the University of Koblenz-Landau, and Philipp Mayr of GESIS.

Since the social sciences are given only marginal coverage in the main bibliographic databases, this project aims to make more citation data available to researchers, with a particular focus on the German language social sciences. It has developed a set of algorithms for the extraction of reference information from PDF documents and for matching the reference entry strings thus obtained against bibliographic databases (see EXCITE git https://github.com/exciteproject/). It is using as its data sources the following Social Science collections: full texts from SSOAR, the Gesis Social Science Open Access Repository (https://www.gesis.org/ssoar/home/) and scattered pdf stocks from other social science collections including SOLIS, Springer Online Journals and CSA Sociological Abstracts [4, 5].

The EXCITE project organized an international developer and researcher workshop “Challenges in Extracting and Managing References” in March 2017 in Cologne. http://west.uni-koblenz.de/en/research/excite/workshop-2017

EXCITE will then structure the extracted bibliographic and citation data in RDF using the OpenCitations Data Model, and will use the OpenCitations Corpus as its publication platform, employing the OCC EXCITE supplier prefix 0110, described here, to identify the provenance of these citations.

References

[4] Martin Körner (2016). Extraction from social science research papers using conditional random fields and distant supervision, Master’s Thesis, University of Koblenz-Landau, 2016.

[5] Körner, M., Ghavimi, B., Mayr, P., Hartmann, H., & Staab, S. (2017). Evaluating reference string extraction using line-based conditional random fields: a case study with german language publications. In M. Kirikova, K. Nørvåg, G. A. Papadopoulos, J. Gamper, R. Wrembel, J. Darmont, & S. Rizzi (Hrsg.), New Trends in Databases and Information Systems (Bd. 767, S. 137–145). Springer International Publishing. https://doi.org/10.1007/978-3-319-67162-8_15 Preprint: https://philippmayr.github.io/papers/Koerner-et-al2017.pdf

3 The Venice Scholar Index

The Venice Scholar Index is a citation index of literature on the history of Venice, indexing nearly 3000 volumes of scholarship from the mid 19^th century to 2013, from which some 4 million bibliographic references have been extracted.

The Venice Scholar Index is the first prototype resulting from Linked Books Project (https://dhlab.epfl.ch/page-127959-en.html), a project spearheaded by Giovanni Colavizza and Matteo Romanello of the Digital Humanities Laboratory at EPFL (École Polytechnique Fédérale de Lausanne), with partners in Venice, Milan and Rome.

The project is exploring the history of Venice through references to scholarly literature as well as archival documents found within publications. To achieve this goal, the project has developed a system to automatically extract bibliographic references found within a large set of digitized books and journals, which has then been applied to the publications on the history of Venice, its main use case [6].

The Linked Books Project is specifically interested in analysing the interplay between citations to primary (e.g. archival) documents and those to secondary sources (scholarly literature), and the citation profiles of publications through time. To this end, it developed the Venice Scholar Index, a rich search interface to navigate through the resulting network of citations, with the final aim of interlinking digital archives and digital libraries.

The citation data underlying the Venice Scholar Index are modelled using the OpenCitations Data Model, and will use the OpenCitations Corpus as its publication platform, using the OCC Venice Scholar Index supplier prefix 0120 to identify the provenance of these citations.

Reference

[6] Giovanni Colavizza, Matteo Romanello, and Frédéric Kaplan (2017). The references of references: a method to enrich humanities library catalogs with citation data. In International Journal on Digital Libraries 18 (March 8, 2017): 1–11. https://doi.org/10.1007/s00799-017-0210-1.

4 CitEcCyr – Citations in Economics published in CyrillicCitEcCyr (https://github.com/citeccyr/CitEcCyr) is an open repository of citation relationships obtained from research papers in the Russian language and Cyrillic script from Socionet (https://socionet.ru/) and RePEc (http://repec.org/) [7, 8]. The CitEcCyr project is headed by Oxana Medvedeva, is technically led by Sergey Parinov, and is funded by RANEPA (http://www.ranepa.ru/eng/), the Russian Presidential Academy of National Economy and Public. CitEcCyr is also developing a suite of open software for the citation content analysis of these papers. This project intends to model its citations using the OpenCitations Data Model, and will use the OpenCitations Corpus as its publication platform, using the OCC CitEcCyr supplier prefix 0140 to identify the provenance of these citations.

However, since this is the first project from which OpenCitations will be importing bibliographic metadata and citations in a language other than English and in a script other than the Latin script, we at OpenCitations are going to have to crawl out of our comfortable ‘Western’ shells and learn to handle foreign languages and scripts other than Latin scripts.

For Russian language papers written using Cyrillic script, we at OpenCitations will to decide how best to handle Russian language written using Cyrillic script, Cyrillic script transliterated into Latin script, and Russian language translated into English and rendered using Latin script. In particular, since in the OpenCitations Corpus our reference entry records are the uncorrected literal texts of the references in the reference lists of the citing papers, these will need to be recorded as given in Cyrillic.

We will need to develop a policy for when to provide Latin script translations of (for example) titles and abstracts, if these are not provided by the data supplier. To facilitate use of the OpenCitations Corpus by Russian scholars, we will also need to modify the OpenCitations web site, so as to render the static information displayed in the web pages in the language and script appropriate to the language setting on the user’s web browser.

Unfortunately, all this will take time, so we do not anticipate publishing citation data from the CitEcCyr project within OCC any time soon. However, this collaboration will be of tremendous value to OpenCitations as well as to CitEcCyr, since the lessons learned by our collaboration with the CitEcCyr project will enable the OpenCitations Corpus to handle citation data not just in Russian, but also in Arabic, Chinese, Japanese and other languages where the Latin script is not used, something that is not found in other major bibliographic databases.

Watch this space!

References

[7] Jose Manuel Barrueco, Thomas Krichel, Sergey Parinov, Victor Lyapunov, Oxana Medvedeva and Varvara Sergeeva (2017). Towards open data for the citation content analysis. https://arxiv.org/abs/1710.00302

[8] Thomas Krichel (2017). CitEc to CitEcCyr – A stab at distributed citation systems. Presented at the 2017 EXCITE workshop. http://west.uni-koblenz.de/sites/default/files/research/projects/excite/workshop-2017/slides/excite-workshop-2017_krichel_citec-to-citeccyr.pdf

OpenCitations and the Initiative for Open Citations: A Clarification

Some folk are confused, but OpenCitations and the Initiative for Open Citations, despite the similarity of their names, are two distinct organizations.

OpenCitations (http://opencitations.net) is an open scholarly infrastructure organization directed by Silvio Peroni and myself, and its primary purpose is to host and build the OpenCitations Corpus (OCC), an RDF database of scholarly citation data that now contains almost 13 million citation links.

In contrast, the Initiative for Open Citations (I4OC; https://i4oc.org) is a separate and independent organization, whose founding was spearheaded by Dario Taraborelli of the WikiMedia Foundation. OpenCitations was just one of several organizations that founded the Initiative for Open Citations, as documented at https://i4oc.org/#founders.

I4OC is a collaboration between scholarly publishers, researchers, and other interested parties to promote the unrestricted availability of scholarly citation data, but it does not itself host citation data.

Within a short space of time, I4OC has persuaded most of the major scholarly publishers to open their reference lists submitted to Crossref, so that the proportion of all references submitted to Crossref that are now open has risen from 1% to over 50%.

These references are now available for OpenCitations to harvest into the OpenCitations Corpus and publish in RDF, as well as for others to harvest and use as they wish.

All clear now?

Oxford University Press opens its references!

Good news! Today, on January 16th 2018, Oxford University Press (OUP) announced its participation in the Initiative for Open Citations, and requested Crossref to turn on reference sharing for all OUP deposited references from more than half a million publications. Oxford University Press is the largest university press in the world, publishing in 70 languages and 190 countries.

Their announcement is at https://academic.oup.com/journals/pages/announcements_from_oup/oup_joins_I4OC.

OUP now joins the elite band of four university presses that have already made their references open at Crossref in response to the I4OC call (https://i4oc.org/#publishers).

This decision by OUP has been a long time in gestation – see my 2012 post Oxford University Press to support Open Citations – but is no less welcome for that!

Funders should mandate open citations

On 9th January 2018, I published a World View article in Nature entitled Funders should mandate open citations [1], in which I argue that access to open references from scholarly publications is so important that, when encouragements from organisations such as the Initiative for Open Citations (I4OC) to publishers to open their references fall on deaf ears, then sterner measures are required.

Specifically, major funders should extend their open access mandates and require grant recipients to publish only in journals whose publishers ensure their references are open.

This suggestion was originally made by Catriona MacCallum, Director of Open Science at Hindawi, during a recent I4OC conference call, and she deserves the credit for it.

My article is freely available from Nature:

online at http://go.nature.com/2midnzx; PDF at http://rdcu.be/Eqsv.

[1] David Shotton (2018). Funders should mandate open citations. Nature 553: 129. doi:10.1038/d41586-018-00104-7

Barriers to comprehensive reference availability

Two significant barriers prevent comprehensive reference availability through Crossref.

The first barrier

First, two-thirds of Crossref’s publisher-members, in particular the smaller ones, do not submit references along with the other details of their publications. Many of these published works are of types (e.g. abstracts, editorials and news items) that lack any references. However, while the number of non-submitted references associated with other publications from these publishers is not known, it is likely to be substantial.

Ironically, quite a number of publishers have their Crossref reference status option set to ‘Open’, and yet fail to submit any references!

All publishers who use Crossref DOIs and submit metadata describing their works to Crossref should be strongly encouraged to start submitting associated reference lists if these exist. Crossref have confirmed that it is easy to do, with or without membership of Crossref’s free and beneficial Cited-by Service that provides publishers with statistics on the citations of their own publications. Help can be provided by Crossref Support (support@crossref.org).

The second barrier

The second barrier to full reference availability is created by publishers that submit references to Crossref, but do not presently make them open. Elsevier is by far the largest member of this group, which also includes the American Chemical Society, IEEE and Wolters Kluwer Health.

It is both quick and easy for a publisher to change its preference setting and request that all the references associated with its DOI prefixes are made open – all it requires is an email request to support@crossref.org. But without such a request, the references will be remain in the default ‘Limited’ status.

References that are not associated with Crossref

There are, of course, many scholarly publications, for example preprints in repositories such as arXiv, and journal articles and monographs from small academic publishers in the Humanities, that do not have Digital Object Identifiers issued by Crossref. There are also an increasing number of datasets in repositories such as Dryad that have associated references to the scholarly literature, but whose DOIs are issued by DataCite. None of these submit references to Crossref where they can be made available via the Crossref API, and separate additional measures will be required to capture and share their references with the community.

The new Crossref reference distribution policy

Since 1st January 2018, Crossref has had a new reference distribution policy, described at https://www.crossref.org/reference-distribution/.

There are three possible options for setting the reference distribution preference from which a publisher can choose, these being ‘Closed’, ‘Limited’ and ‘Open”.

If the ‘Closed’ option is chosen, the references will only be used for the Crossref Cited-by service, and are not distributed via any of the other Crossref interfaces.

If the ‘Limited’ option is chosen, the references will additionally be made available to Crossref metadata subscribers who have signed an agreement for the new Crossref Metadata APIs ‘Plus’ service which also came into effect on 1st January 2018. This is the new Crossref default option.

If the ‘Open’ option is chosen, the references will be openly available to anyone using the Crossref APIs.

Publishers will no longer be able to select the reference distribution preference for individual publications on a case-by-case basis, but rather the preference will be set for all publications appearing under a particular DOI prefix, with the new default option being ‘Limited’.

To date, more than 60 scholarly publishers, including most of the major ones, have responded to the Initiative for Open Citations and have instructed Crossref to set their references to open, as describe in a previous post.