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California Digital Library Supports the Initiative for Open Citations

The California Digital Library, along with 33 other stakeholders and 29 journal publishers, recently signed on to support the Initiative for Open Citations which will free citation data to the public. Daniella Lowenberg, Research Data Specialist / Dash Product Manager at CDL, wrote this post for the CDL Data Pub blog to announce CDL’s support for the initiative. We’re cross posting it here at the OSC blog to help spread the word.

California Digital Library (CDL) is proud to announce our formal endorsement for the Initiative for Open Citations (I4OC). CDL has long supported free and reusable scholarly work, as well as organizations and initiatives supporting citations in publication. With a growing database of literature and research data citations, there is a need for an open global network of citation data.

The Initiative for Open Citations will work with Crossref and their Cited-by service to open up all references indexed in Crossref. Many publishers and stakeholders have opted in to participate in opening up their citation data, and we hope that each year this list will grow to encompass all fields of publication. Furthermore, we are looking forward to seeing how research data citations will be a part of this discussion.

CDL is a firm believer in and advocate for data citations and persistent identifiers in scholarly work. However, if research publications are cited and those citations are not freely accessible and searchable- our goal is not accomplished. We are proud to support the Initiative for Open Citations and invite you to get in touch with any questions you may have about the need for open citations or ways to be an advocate for this necessary change.

Below are some Frequently Asked Questions about the need, ways to get involved, and misconceptions regarding citations. The answers are provided by the Board and founders of the I4OC Initiative:

I am a scholarly publisher not enrolled in the Cited-by service. How do I enable it?

If not already a participant in Cited-by, a Crossref member can register for this service free-of-charge. Having done so, there is nothing further the publisher needs to do to ‘open’ its reference data, other than to give its consent to Crossref, since participation in Cited-by alone does not automatically make these references available via Crossref’s standard APIs.

I am a scholarly publisher already depositing references to Crossref. How do I publicly release them?

We encourage all publishers to make their reference metadata publicly available. If you are already submitting article metadata to Crossref as a participant in their Cited-by service, opening them can be achieved in a matter of days. Publishers can easily and freely achieve this:

  • either by contacting Crossref support directly by e-mail, asking them to turn on reference distribution for all of the relevant DOI prefixes;
  • or by themselves setting the < reference_distribution_opt > metadata element to “ any ” for each DOI deposit for which they want to make references openly available.

How do I access open citation data?

Once made open, the references for individual scholarly publications may be accessed immediately through the Crossref REST API.

Open citations are also available from the OpenCitations Corpus , a database created to house scholarly citations, that is progressively and systematically harvested citation data from Crossref and other sources. An advantage of accessing citation data from the OpenCitations Corpus is that they are available in standards-compliant machine-readable RDF format , and include information about both incoming and outgoing citations of bibliographic resources (published articles and books).

Does this initiative cover future citations only or also historical data?

Both. All DOIs under a prefix set for open reference distribution will have open references through Crossref, for past, present, and future publications.

Past and present publications that lack DOIs are not dealt with by Crossref, and gaining access to their citation data will require separate initiatives by their publishers or others to extract and openly publish those references.

Under what licensing terms is citation data being made available?

Crossref exposes article and reference metadata without a license, since it regards these as raw facts that cannot be licensed.

The structured citation metadata within the OpenCitations Corpus are published under a Creative Commons CC0 public domain dedication, to make it explicitly clear that these data are open.

My journal is open access. Aren’t its articles’ citations automatically available?

No. Although Open Access articles may be open and freely available to read on the publisher’s website, their references are not separate, and are not necessarily structured or accessible programmatically. Additionally, although their reference metadata may be submitted to Crossref, Crossref historically set the default for references to “closed,” with a manual opt-in being required for public references. Many publisher members have not been aware that they could simply instruct Crossref to make references open, and, as a neutral party, Crossref has not promoted the public reference option. All publishers therefore have to opt in to open distribution of references via Crossref.

Is there a programmatic way to check whether a publisher’s or journal’s citation data is free to reuse?

For Crossref metadata , their REST API reveals how many and which publishers have opened references. Any system or tool (or a JSON viewer) can be pointed to this query: http://api.crossref.org/members?filter=has-public-references:true&rows=1000 to show the count and the list of publishers with “ public-references “: true .

To query a specific publisher’s status, use, for example:

http://api.crossref.org/members?filter=has-public-references:true&rows=1000&qu ery=springer then find the tag for public-references. In some cases it will be set to false.


You can contact the founding group by e-mail at: info@i4oc.org .

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