@misc{OWLSemantics,
  title = "OWL 2 Web Ontology Language: Direct Semantics",
  author = "Boris Motik, Peter F. Patel-Schneider and Bernardo {Cuenca Grau}",
  year = "2009",
  howpublished = "World Wide Web Consortium (W3C)  Recommendation",
  url = "http://www.w3.org/TR/2009/CR-owl2-direct-semantics-20090611/",
}