John K. Debenham A Unified Model Maintains Knowledge Base Integrity. 21-27 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2773&spage=21 2003 conf/kes/2003-1 KES db/conf/kes/kes2003-1.html#Debenham03