Cristina Conati Heather Maclaren Evaluating a Probabilistic Model of Student Affect. 55-66 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3220&spage=55 2004 conf/its/2004 Intelligent Tutoring Systems db/conf/its/its2004.html#ConatiM04