Reference for “OWL 2 Web Ontology Language Direct Semantics”

@TechReport{Patel-Schneider:09:OWO,
  author      = "Peter F. Patel-Schneider and Boris Motik and Bernardo Cuenca Grau",
  title       = "{OWL} 2 Web Ontology Language Direct Semantics",
  month       = oct,
  note        = "http://www.w3.org/TR/2009/REC-owl2-direct-semantics-20091027/",
  year        = "2009",
  bibsource   = "http://w2.syronex.com/jmr/w3c-biblio",
  type        = "{W3C} Recommendation",
  institution = "W3C",
}