OpenCitations
Citations are the links that knit together our scientific and cultural knowledge
However often they are enclosed in closed citation indexes thought only for human consumption and/or accessible only by paying significant fees
The OpenCitations Corpus (OCC, http://opencitations.net) is a LOD repository of CC0 citation data described with SPAR Ontologies (http://www.sparontologies.net)
It provides >11M citation links from ~260,000 citing articles to ~6M cited resources + provenance information
Ingestion workflow
We developed several scripts for implementing the ingestion workflow that populates the OpenCitations Corpus
All the software is available on the OpenCitations GitHub repository and released as open source code with the ISC License
These scripts implement a live and iterative process
Live: it's working while I'm speaking. It doesn't sleep, never. It's like a sentient, relentless, fast zombie – watch out!Iterative: the ingestion workflow continuously calls several external APIs to obtain new reference lists and clean metadata of the citing and cited papers
External APIs
At present, all the reference lists are taken by processing the XML sources of the papers in the PubMed Central Open Access subset
Europe PubMed Central API for retrieving the XML sources
We ask for the most recent papers first
Citing papers includes articles published in 2016 and 2017
There are 1.75M OA articles available in PubMed, according to their API. We have harvested 15% so far...
Crossref APIs to obtain additional information (title, authors, venues, etc.) about citing/cited papers, and then call the ORCID APIs to obtain ORCIDs of the authors
Data model
Available at https://doi.org/10.6084/m9.figshare.3443876 and implemented in the OpenCitations Ontology
Resources in the OCC
| Entity type | What it describes | Count in the OCC |
|---|---|---|
| Bibliographic resource (br) | Conference papers, book chapters, journal articles, academic proceedings, books, journals, etc. | ~7.3M |
| Resource embodiment (re) | Digital vs. print, first and ending pages, etc. | ~4.3M |
| Bibliographic entry (be) | Textual content of a reference in a reference list | ~10.5M |
| Resposible agent (ra) | Given name, family name and ORCID of the agent involved | ~22.5M |
| Agent role (ar) | Author, publisher, etc. | ~28.6M |
| Identifier (id) | DOI, PubMed ID, PubMed Central ID, ORCID, ISSN, etc. | ~15.1M |
| Data statements | Provenance statements |
|---|---|
| ~0.45B | ~1.5B |
Entities in the OCC
| Entity type | Kinds of entity | Entities with identifiers |
|---|---|---|
| Bibliographic resource |
Academic Proceedings: 13,804 Book: 47,824 Book Chapter: 68,798 Book Series: 15 Data File: 4,155 Expression Collection: 10,321 Journal: 27,373 Journal Article: 4,481,224 Journal Issue: 1,029,369 Journal Volume: 365,286 Part: 6 Proceedings Paper: 28,125 Reference Book: 66 Reference Entry: 7,917 Report Document: 1,946 Series: 155 Specification Document: 600 Thesis: 768 Generic kind: 1,281,627 |
DOI: 4,697,326 ISBN: 82,329 ISSN: 38,359 PMCID: 1,280,229 PMID: 3,954,683 URL: 4,835,585 |
| Responsible agent | - |
ORCID: 240,989 URL: 5,642 |
| Identifier |
DOI: 4,697,326 ISBN: 82,329 ISSN: 38,359 ORCID: 240,989 PMCID: 1,280,229 PMID: 3,954,683 URL: 4,841,227 |
- |
FAIR citation data
More details: http://w3id.org/people/essepuntato/papers/oc-garr2017.html
Accessing OCC data
Direct access to bibliographic resources by means of their HTTP URIs (via content negotiation, e.g. https://w3id.org/oc/corpus/br/1)
SPARQL endpoint (https://w3id.org/oc/sparql)
Monthly dumps (http://opencitations.net/download, stored in Figshare)
Dump views and downloads
Usage of the OCC
Some known adopters: Wikidata, OpenAIRE, LOC-DB, eLife, Ontotext, independent researchers (Anna Kamińska, Daniel Himmelstein, Thiago Nunes and Daniel Schwabe)
Website accesses
Use by country: United States (33.7%), France (31.3%), Bulgaria (14.3%)
Blog
OpenCitations Blog on Wordpress at https://opencitations.wordpress.com
OpenCitations Twitter account at https://twitter.com/opencitations
I4OC
The Initiative for Open Citations (I4OC, https://i4oc.org) is a collaboration between scholarly publishers, researchers, and other interested parties to promote the unrestricted availability of scholarly citation data
Goal: promote the availability of data on citations that are available in machine-readable formats, decoupled from the source they have been extracted, freely accessible and usable
What happened: before I4OC launch (6 April 2017), 1% of publications in Crossref with open references
Current and future infrastructure
It's a virtual machine! It doesn't exist
DELL PowerEdge R730xd V4, 512GB RAM, 22TB HD + 30 Raspberry Pi 3
We have recently received a small grant from the Sloan Foundation for one year's salary for a postdoc to develop new user interfaces, and new hardware to enhance the OCC performance - from 8M citations per year to 240M
Data are coming
