"Identifier"@en . "An unambiguous reference to the resource within a given context."@en . "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 . . . "2008-01-14"^^ . . . .