The OpenCitations Meta database stores and delivers bibliographic metadata for all publications involved in the OpenCitations Index.
For each publication, the metadata exposed by OpenCitations Meta includes the publication's title, type, venue (e.g. journal name), volume number, issue number, page numbers,
Currently, OpenCitations Meta contains:
114,703,611 bibliographic entities
343,715,548 authors and 2,533,136 editors (counted by their roles, without disambiguating individuals)
711,711 publication venues
241,783 publishers
OpenCitations Meta was first released on 20 December 2022.
Each entity is identified by a URI structured as follows: https://w3id.org/oc/meta/[[OMID]]
Every entity in OpenCitations Meta is assigned persistent internal identifier called OpenCitations Meta Identifier (OMID). The OMID has structure [[entity_type_abbreviation]]/[[supplier_prefix]][[sequential_number]].
For example, the first journal article ever processed has OMID br/0601 (the full URI is https://w3id.org/oc/meta/br/0601), where br is the abbreviation of bibliographic resource, and 060 corresponds to the supplier prefix, helpful in recognising at a glance the index it belongs to (i.e., OpenCitations Meta). Finally, 1 indicates that this is the index's first bibliographic resource ever minted.
The entities subject to deduplication and associated with an OMID are identifiers (abbr. id), agent roles (i.e., authors, editors, publishers, abbr. ar),
responsible agents (i.e., people and organisations, abbr. ra), resource embodiments (i.e., pages, abbr. re),
venues, volumes, and issues (which are all bibliographic resources, abbr. br).
On the contrary, titles, types, and dates are treated as literal values, not entities.
All the data in OpenCitations Meta:
can be queried by means of the OpenCitations Meta SPARQL endpoint;
can be retrieved by using the META REST API;