Michel Chein Marie-Laure Mugnier Concept Types and Coreference in Simple Conceptual Graphs. 303-318 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3127&spage=303 2004 conf/iccs/2004 ICCS db/conf/iccs/iccs2004.html#CheinM04