July 11, 2017

Availability of open reference data nears 50% as major societies and influential publishers endorse the Initiative for Open Citations

(San Francisco, California) July 11, 2017 - In the days immediately following the launch of the Initiative for Open Citations (I4OC) in April this year, some major names in scholarly publishing made the decision to release their reference data into the public domain. Three months on, a further 16 publishers have added their names to the list and the percentage of articles with open reference data has moved from 40% to over 45%. That’s more than 16 million articles with open references.

Among the 20 publishers who contribute the largest amount of citation data, those who are making their citation data freely available, now include: AIP Publishing, the American Institute of Aeronautics and Astronautics, the American Physical Society, De Gruyter, Emerald, and SciELO. They join Wiley, SAGE, Springer Nature, Taylor & Francis and many others who made their reference data available prior to, or as part of, the launch of I4OC. Out of the 20 largest contributors, 13 publishers have now moved their reference data into the public domain, and discussions are ongoing with several other publishers.

Outside of the top largest contributors, many more scientific publishing organisations are also supporting I4OC, notably the American Association for the Advancement of Science (AAAS) – publishers of Science magazine and others, the Proceedings of the National Academy of Sciences (PNAS), and three further society publishers: the American Society for Cell Biology, the American Society for Biochemistry and Molecular Biology and the Electrochemical Society. They follow the lead already shown, for example, by the American Geophysical Union, the Association for Computing Machinery, and the Royal Society. Other publishers who have moved to release reference data since the launch of I4OC are AOSIS, InTechOpen, IOS Press, MDPI and World Scientific Publishing.

We are also thrilled to announce that more organizations are joining our list of stakeholders endorsing the initiative, including the Allen Institute for Artificial Intelligence, the Association of European Research Libraries (LIBER), the Centre for Science and Technology Studies at Leiden University (CWTS), CORE, Jisc, the Open Access Scholarly Publishers Association (OASPA), and ScienceOpen.

With over 40 publishers now leading the way, we call on all 900+ remaining publishers, particularly the smaller publishers who deposit reference data at Crossref, to join this initiative and make their reference data open.

Making the data publicly available is simple. To release your reference data, please send a request to [email protected].

We’ll report back in three months with an update on how many additional publishers have switched their reference data to open.

Press Release

Initiative for Open Citations (I4OC) launches with early success

(San Francisco, California) April 6, 2017 - There is fresh momentum in the scholarly publishing world to open up data on the citations that link research publications.

Six organizations today announced the establishment of the Initiative for Open Citations (I4OC): OpenCitations, the Wikimedia Foundation, PLOS, eLife, DataCite, and the Centre for Culture and Technology at Curtin University.

Until recently, the vast majority of citation data were not openly available, even though all major publishers freely share their metadata through the foundational infrastructure provided by Crossref. Before I4OC started, only about 1% of the publications with reference data deposited in Crossref made their references freely available. Now, that figure will jump to 40%.[1] In recent months, several publishers have made the decision to release these metadata publicly, including the American Geophysical Union, Association for Computing Machinery, BMJ, Cambridge University Press, Cold Spring Harbor Laboratory Press, EMBO Press, Royal Society of Chemistry, SAGE Publishing, Springer Nature, Taylor & Francis, and Wiley. These decisions stem from discussions that have been taking place since a call-to-action to open up citations was made by Dario Taraborelli of the Wikimedia Foundation at the 2016 OASPA Conference on Open-Access Publishing. These publishers join other publishers who have been opening their references through Crossref for some time (see full list).

The purpose of I4OC is to coordinate these efforts and to promote the creation of a comprehensive, freely-available corpus of scholarly citation data. Such a corpus will be valuable for new as well as existing services, and will allow many more interested parties to explore, mine, and reuse the data for new knowledge.

The key benefits that arise from a fully open citation dataset include:

  • The establishment of a global public web of linked scholarly citation data to enhance the discoverability of published content, both subscription access and open access. This will particularly benefit individuals who are not members of academic institutions with subscriptions to commercial citation databases.
  • The ability to build new services over the open citation data, for the benefit of publishers, researchers, funding agencies, academic institutions and the general public, as well as enhancing existing services.
  • The creation of a public citation graph to explore connections between knowledge fields, and to follow the evolution of ideas and scholarly disciplines.

The Internet Archive, Mozilla, the Bill & Melinda Gates Foundation, the Wellcome Trust, and 29 other projects and organizations have formally put their names behind I4OC as stakeholders in support of openly accessible citations.

The creation of I4OC was spearheaded by Jonathan Dugan, Martin Fenner, Jan Gerlach, Catriona MacCallum, Daniel Mietchen, Cameron Neylon, Mark Patterson, Michelle Paulson, Silvio Peroni, David Shotton, and Dario Taraborelli.

Dario Taraborelli, Head of Research at the Wikimedia Foundation, said: “Citations are the foundation for how we know what we know. Today, tens of millions of scholarly citations become available to the public with no copyright restriction. We look forward to more organizations joining this initiative to release, and build on this data.”

Liz Ferguson, VP Publishing Development, Wiley, said: “Wiley is delighted to support I4OC by opening our citation metadata via Crossref. Collaborating with other publishers further contributes to sustainable and standardized infrastructure that will benefit the research community. We are particularly excited by the potential to expose networks of research that would otherwise lie hidden or take years to discover.”

Robert Kiley, Head of Open Research at the Wellcome Trust, said: “The open availability of citation data will help all funders better evaluate the research they fund. The progress that I4OC has made is an essential first step and we encourage all publishers to publicly share this data.”

Mark Patterson, Executive Director of eLife, said: “It’s fantastic to see the interest that’s being shown by so many publishers in making their reference list metadata publicly available. We hope that this new momentum will encourage all publishers to follow suit, and that new services and tools can be built around this open data.”

David Shotton (University of Oxford) and Silvio Peroni (University of Bologna), Co-Directors of OpenCitations, said: "OpenCitations harvests scholarly citation information from Crossref and other authoritative sources, and makes it freely available for others to use and build upon. We are delighted to be a founding partner of I4OC, and encourage those remaining publishers whose journal article reference lists are still closed to embrace this sea change in attitude towards open citation data.”

Catriona MacCallum Advocacy Director, PLOS, said: “Creating an open database of citations will allow researchers to perform independent analyses of how scientific ideas are communicated through article citations, and a transparent way of tracking the influence of particular articles. By opening up these metadata via Crossref, publishers are providing a vital contribution to Open Science.”

Many other publishers have expressed interest in opening up their reference data. They can do this via Crossref, with a simple email to [email protected] requesting they turn on reference distribution for all their DOI prefixes. I4OC will provide regular updates on the growth of the public citation corpus, how the data is being used, additional stakeholders and participating publishers as they join, and as new services are developed.

[1] percentage of publications with open references out of the total number of publications with reference metadata deposited with Crossref. As of March 2017, nearly 35 million articles with references have been registered with Crossref. Citation data from the Crossref REST API will be made available shortly after the announcement.

Download a PDF of the press release

Participating publishers

  • American Geophysical Union
  • Association for Computing Machinery
  • BMJ
  • Cambridge University Press
  • Co-Action Publishing
  • Cold Spring Harbor Laboratory Press
  • Copernicus GmbH
  • eLife
  • EMBO Press
  • Faculty of 1000, Ltd.
  • Frontiers Media SA
  • Geological Society of London
  • Hamad bin Khalifa University Press (HBKU Press)
  • Hindawi
  • International Union of Crystallography
  • Leibniz Institute for Psychology Information
  • MIT Press
  • PeerJ
  • Pensoft Publishers
  • Portland Press
  • Public Library of Science
  • Royal Society of Chemistry
  • SAGE Publishing
  • Springer Nature
  • Taylor & Francis Group
  • The Rockefeller University Press
  • The Royal Society
  • Ubiquity Press, Ltd.
  • Wiley

Founding organizations

  • OpenCitations
  • Wikimedia Foundation
  • Public Library of Science
  • eLife
  • DataCite
  • Centre for Culture and Technology, Curtin University


  • Alfred P. Sloan Foundation
  • Altmetric
  • Association of Research Libraries
  • Authorea
  • Bill & Melinda Gates Foundation
  • California Digital Library
  • Center for Open Science
  • Coko Foundation
  • Confederation of Open Access Repositories
  • ContentMine
  • Data Carpentry
  • Dataverse
  • Department of Computer Science and Engineering, University of Bologna
  • dblp: computer science bibliography
  • Dryad
  • Figshare
  • ImpactStory
  • Internet Archive
  • Knowledge Lab
  • Max Planck Digital Library
  • Mozilla
  • Open Knowledge International
  • OpenAIRE
  • Overleaf
  • Project Jupyter
  • rOpenSci
  • Science Sandbox
  • Wellcome Trust
  • Wiki Education Foundation
  • Wikimedia Deutschland
  • Wikimedia UK
  • Zotero