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.
Richesson RL, Fung KW, Krischer JP.Heterogeneous but 'Standard' Coding Systems for Adverse Events: Issues in Achieving Interoperability Between Apples and Oranges Contemp Clin Trials. 2008 Sep;29(5):635-45. Epub 2008 Mar 5
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.
Cheung NT, Fung K, Wong KC, Cheung A, Cheung J, Ho W, Cheung C, Shung E, Fung V, Fung H.Medical Informatics--the State of the Art In the Hospital Authority. Int J Med Inform. July 2001;62(2-3):113-9.
Fung K, Lau Y, Fielding R, Or A, Yip AW.The impact of mastectomy, breast-conserving treatment and immediate breast reconstruction on the quality of life of Chinese women. ANZ J Surg. April 2001;71(4):202-6.