Initiative for Open Citations

Mike's Notes

I discovered a reference to the Initiative for Open Citations (I4OC) in the 2018 annual report from the Wikimedia Foundation's technology department.

It looks advantageous and needs to be integrated into the Pipi 9 reference engine.

OpenCitations is hosted by the University of Bologna and has massive, freely available datasets.

Resources

• https://wikimediafoundation.org/news/2018/01/09/technology-department-highlights/
• https://i4oc.org
• https://opencitations.net

References

• Reference

Repository

• Home > Ajabbi Research > Library >
• Home > Handbook > 

Last Updated

17/05/2025

Initiative for Open Citations

By: Mike Peters

i40c.org: 14/01/2025

From the I4OC home page accessed 14/01/2025

The Initiative for Open Citations I4OC is a collaboration between scholarly publishers, researchers, and other interested parties to promote the unrestricted availability of scholarly citation data.

About

Citations are the links that knit together our scientific and cultural knowledge. They are primary data that provide both provenance and an explanation for how we know facts. They allow us to attribute and credit scientific contributions, and they enable the evaluation of research and its impacts. In sum, citations are the most important vehicle for the discovery, dissemination, and evaluation of all scholarly knowledge.

As the number of scholarly publications is estimated to double every nine years, citations – and the computational systems that track them – enable researchers and the public to keep abreast of significant developments in any given field. For this to be possible, it is essential to have unrestricted access to bibliographic and citation data in machine-readable form.

The present scholarly communication system inadequately exposes the knowledge networks that already exist within our literature. Citation data are not usually freely available to access, they are often subject to inconsistent, hard-to-parse licenses, and they are usually not machine-readable.

An initiative to open up citation data

The aim of this initiative is to promote the availability of data on citations that are structured, separable, and open.

Structured means the data representing each publication and each citation instance are expressed in common, machine-readable formats, and that these data can be accessed programmatically. Separable means the citation instances can be accessed and analyzed without the need to access the source bibliographic products (such as journal articles and books) in which the citations are created. Open means the data are freely accessible and reusable.

Key benefits of achieving this aim 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.

Reference distribution

Many publishers currently deposit reference lists from their journal articles to Crossref as part of their participation in Crossref’s Cited-by service. To open their references, along with the other bibliographic metadata that publishers send to Crossref, publishers need to turn on reference distribution for all of the Digital Object Identifier (DOI) prefixes they manage. This step allows references within the Crossref members’ articles to be distributed without restriction through all of Crossref's Metadata Delivery services, including the REST API and bulk metadata dumps, to any interested party. See below for additional information on reference distribution and on how to participate in Crossref’s Cited-by service.

Relationship with other initiatives

I4OC is part of a broader movement for promoting openness of bibliographic metadata. In particular, I4OC has a close relationship with the Initiative for Open Abstracts (I4OA), a sister initiative of I4OC aimed at promoting openness of abstracts of scholarly publications. I4OC and I4OA are managed by different teams, but these teams consist partly of the same individuals. While we hope that scholarly publishers will make a general commitment to openness of bibliographic metadata and will support both initiatives, it is possible for a publisher to support I4OC without supporting I4OA, or vice versa.

Participating publishers

Before I4OC started, publishers releasing references in the open accounted for just 1% of citation metadata collected annually by Crossref. Following discussions over the past months, several subscription-access and open-access publishers have recently made the decision to release reference list metadata publicly. These include: 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 publishers join other publishers who have been opening their references through Crossref for some time.

Starting from 3rd June 2022 all the members of Crossref cannot limit the distribution of their references. All the members that previously had limited or closed references have now been set to open. This means that all the currently deposited references in Crossref are now treated as open metadata. You can read the dedicated blog post explaining the new membership terms of Crossref.

The following list includes the names of all those publishers who, as of August 16, 2022, have submitted to Crossref the references from at least one publication bearing a Crossref DOI. I4OC updates this list, which presently includes about 5,343 names, every two months.

There are more than 13,000 additional publishers who are depositing publication metadata with Crossref, but who are failing to submit references with the other publication metadata. I4OC appeals to these publishers to start depositing their publication references, and other rich metadata including publication abstracts, ORCID author identifiers, and funder information, along with the basic metadata they already submit to Crossref.

[A list of the names of 100's of institutions was omitted from this page; see the original]

How many citations are open today?

As of August 2022, the fraction of publications with open references has grown from 1% to 100% out of 61 million articles with references deposited with Crossref.

We encourage all other scholarly publishers to follow the example of these trail-blazing publishers by making their reference metadata publicly available. Please contact Crossref Support (support@crossref.org) for more information, or to let them know that you are ready to open up your reference metadata now. See also our list of responses to frequently asked questions.

Building on open citations

Several organizations and projects have expressed support for the Initiative for Open Citations and interest in building on and promoting the availability of open citation data. I4OC will keep a list of these projects, and we encourage all other interested parties to make contact with us.