Sean Bechhofer; Alistair Miles. <a href="http://www.w3.org/TR/2009/CR-skos-reference-20090317"><cite>SKOS Simple Knowledge Organization System Reference.</cite></a> 17 March 2009. W3C Candidate Recommendation. (Work in progress.) URL: <a href="http://www.w3.org/TR/2009/CR-skos-reference-20090317">http://www.w3.org/TR/2009/CR-skos-reference-20090317</a>