PMID (PubMed ID) is the unique identifier for a publication's abstract in PubMed.
PMCID (PubMed Central ID) is the unique identifier for a free complete article (once it is publicly available) in PubMed Central.
PubMed and PubMed Central, produced by the U.S. National Library of Medicine, are text archives of biomedical and life sciences literature.
A DOI (Digital Object Identifier) is a publisher’s unique identifier for a publication. The prefix http://dx.doi.org/ is presumed. Publishers may charge for access.
Sun H, Li J, Wu Y, Wang L, Fung K.Using an Ontology-Based Approach to Handle Author Affiliations in a Large Biomedical Citation Database. Stud Health Technol Inform. 2017;245:1338.
Abhyankar S, Callaghan FM, Demner-Fushman D, McDonald CJ.Using informatics tools to study obesity and outcomes after critical illness. NLM Informatics Training Conference 2011, National Institutes of Health (NIH) Campus, Natcher Conference Center, Bethesda, MD, June 28-30, 2011.
Humphrey SM, Rogers W, Kilicoglu H, Demner-Fushman D, Rindflesch TC.Word sense disambiguation by selecting the best semantic type based on journal descriptor indexing: preliminary experiment. J Am Soc Inf Sci Technol. January 2006;57(1):96-113.