"SKOS Simple Knowledge Organization System Reference" . . . _:vb50820131 . . _:vb50820133 . _:vb50820132 "Sean Bechhofer" . . _:vb50820132 . _:vb50820133 . _:vb50820133 . . . . _:vb50820132 . . _:vb50820131 . "2009-08-18" . _:vb50820131 "Alistair Miles" .