Citebase

Citebase Search was an experimental, semi-autonomous citation index for free, online research literature created at the University of Southampton as part of the Open Citation Project.{{Cite thesis|title=Evaluating Research Impact through Open Access to Scholarly Communication|url=https://eprints.soton.ac.uk/263313/|publisher=University of Southampton|date=2006|degree=phd|language=en|first=Timothy|last=Brody}}{{cite web|url=http://iplus.ukoln.ac.uk/technology/citebase|title=Citebase|website=iplus.ukoln.ac.uk|archive-url=https://archive.today/20130706204510/http://iplus.ukoln.ac.uk/technology/citebase|archive-date=2013-07-06|access-date=2013-04-05}}{{Cite journal|last=Shotton|first=David|date=2013-10-17|title=Publishing: Open citations|journal=Nature News|language=en|volume=502|issue=7471|pages=295–297|doi=10.1038/502295a|pmid=24137832|doi-access=free}} It harvested open access e-prints (most author self-archived) from OAI-PMH compliant archives, parses and links their references and indexes the metadata in a Xapian-based search engine.{{Cite journal|last=Harnad|first=Stevan|date=2008-11-14|title=Open access scientometrics and the UK Research Assessment Exercise|url=https://akademiai.com/doi/abs/10.1007/s11192-009-0409-z|journal=Scientometrics|volume=79|issue=1|pages=147–156|doi=10.1007/s11192-009-0409-z|issn=0138-9130|arxiv=cs/0703131|s2cid=3183215}} Citebase went live in 2005 and ceased operation in 2013.{{Cite web|url=http://www.citebase.org/|title=Archive of 2013 citebase home page|archive-url=https://web.archive.org/web/20130115030057/http://www.citebase.org/|access-date=2019-06-07|archive-date=2013-01-15}}

More than three-quarters of the papers indexed were author self-archived in the ArXiv archive, which includes physics, maths and computer science. Some (published) biomedical papers were indexed from BioMed Central and PubMed Central.{{Cite web|url=http://opcit.eprints.org/evaluation/Citebase-evaluation/evaluation-report.html|title=Citebase Evaluation Report: Full Official Version: OpCit |author=Steve Hitchcock |author2=Arouna Woukeu |author3=Tim Brody |author4=Les Carr |author5=Wendy Hall |author6=Stevan Harnad|date=2003|website=opcit.eprints.org}}