"2004-02-10" . _:vb50819241 . _:vb50819243 . . _:vb50819243 . . . _:vb50819242 . . _:vb50819241 . _:vb50819243 . . _:vb50819242 "Ramanathan Guha" . . _:vb50819241 "Dan Brickley" . . _:vb50819242 . "RDF Vocabulary Description Language 1.0: RDF Schema" .