Simone Braun Andreas Schmidt Andreas Walter Gábor Nagypál Valentin Zacharias Ontology Maturing: a Collaborative Web 2.0 Approach to Ontology Engineering. 2007 CKC http://ceur-ws.org/Vol-273/paper14_.pdf conf/www/2007ckc db/conf/www/ckc2007.html#BraunSWNZ07