Joachim Hereth Correia Julia Klinger Protoconcept Graphs: The Lattice of Conceptual Contents. 14-27 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2961&spage=14 2004 conf/icfca/2004 ICFCA db/conf/icfca/icfca2004.html#CorreiaK04