Simon Parsons Shaw Greene Argumentation and Qualitative Decision Making. 328-340 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=1638&spage=0328 1999 conf/ecsqaru/1999 ESCQARU db/conf/ecsqaru/ecsqaru1999.html#ParsonsG99