Michel C. A. Klein Atanas Kiryakov Damyan Ognyanov Dieter Fensel Finding and Characterizing Changes in Ontologies. 79-89 2002 conf/er/2002 ER http://link.springer.de/link/service/series/0558/bibs/2503/25030079.htm db/conf/er/er2002.html#KleinKOF02