[1] [CITE@en[RDF Schema 1.1]]
( ([TIME[2014-02-27 21:42:23 +09:00]] 版))
<https://dvcs.w3.org/hg/rdf/raw-file/default/rdf-schema/index.html#h4_ch_subject>

[2] [CITE@en[RDF 1.1 Concepts and Abstract Syntax]]
( ([TIME[2014-04-26 05:27:21 +09:00]] 版))
<https://dvcs.w3.org/hg/rdf/raw-file/default/rdf-concepts/index.html#dfn-subject>