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.
Hristovski D, Kastrin A, Peterlin B, Rindflesch TC.Combining Semantic Relations and DNA Microarray Data for Novel Hypotheses Generation Lecture Notes in Bioinformatics. Springer
Mork JG, Aronson AR.The Medical Text Indexer (MTI) system for indexing biomedical literature. book chapter submitted to monograph Indexing Specialities: Medicine. Edited by L. Pilar Wyman. Medford, NJ: Information Today, Inc., in association with the American Society of Indexers, Phoenix, AZ. 2010.
Simpson MS, Demner-Fushman D.Biomedical Text Mining: A Survey of Recent Progress. In Charu C. Aggarwal and ChengXiang Zhai, Editors. Mining Text Data. (Springer) 2011.