Digital Object Identifier
Identifier
International Standard Name Identifier
Library of Congress Control Number
International Standard Book Number
International Standard Serial Number
Uniform Resource Identifier
PubMed
GND (identifier)
Bibcode
ORCID
Virtual International Authority File
Système universitaire de documentation
PubMed Central
MusicBrainz
JSTOR
Trove
Wikidata
Library Network of Western Switzerland
Semantic Scholar
Mathematical Reviews
Internet Engineering Task Force
ArXiv
OCLC
Internet Movie Database
YouTube