This page is a legacy page (not linked anymore from the official website) that describes DOCI. Since October 2023, all the citation data collected previously in different OpenCitations Indexes have been moved (and deduplicated) in the new citation collection, i.e. the OpenCitations Index.
DOCI, the OpenCitations Index of DataCite open DOI-to-DOI citations, is an RDF dataset containing details of all the citations that are specified in the last dump of 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 contains:
169,822,752 citations;
1,753,858 bibliographic resources.
DOCI was first created and released on 13 December 2022.
Most recent update of DOCI: December 2022, based on the last dump of DataCite dated 22 October 2021.
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]].
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/doci/ci/080010504060836132137200707121027-080010504060836161221130313), 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.
All the data in DOCI:
by querying the SPARQL endpoint of POCI, DOCI and CROCI;
can be retrieved by using the DOCI REST API;
are available as dumps on Figshare in CSV, N-Triples and Scholix.