"Identifier"@en-us . . "2008-01-14"^^ . . "Identifier"@en . . . "An unambiguous reference to the resource within a given context."@en . . "An unambiguous reference to the resource within a given context."@en-us . . . "2008-01-14" . . . . . "Recommended best practice is to identify the resource by means of a string conforming to a formal identification system. "@en-us . "2008-01-14" . "Recommended practice is to identify the resource by means of a string conforming to an identification system. Examples include International Standard Book Number (ISBN), Digital Object Identifier (DOI), and Uniform Resource Name (URN). Persistent identifiers should be provided as HTTP URIs."@en .