Ralf Küsters Ralf Molitor Approximating Most Specific Concepts in Description Logics with Existential Restrictions. 33-47 2001 conf/ki/2001 KI/ÖGAI http://link.springer.de/link/service/series/0558/bibs/2174/21740033.htm db/conf/ki/ki2001.html#KustersM01