A database providing an authoritative source of bibliographic information, for example PubMed (http://www.ncbi.nlm.nih.gov/pubmed), CrossRef Metadata Search (http://search.crossref.org/) and PubMed Central (http://www.ncbi.nlm.nih.gov/pmc/).
A database providing an authoritative source of bibliographic information, for example PubMed (http://www.ncbi.nlm.nih.gov/pubmed), CrossRef Metadata Search (http://search.crossref.org/) and PubMed Central (http://www.ncbi.nlm.nih.gov/pmc/).