Toshinobu Kasai Haruhisa Yamaguchi Kazuo Nagano Riichiro Mizoguchi Goal Transition Model and Its Application for Supporting Teachers based on Ontologies. 330-337 2005 AIED conf/aied/2005 db/conf/aied/aied2005.html#KasaiYNM05 http://www.booksonline.iospress.nl/Content/View.aspx?piid=1326