M. Brian Blake Hassan Gomaa Object-Oriented Modeling Approaches to Agent-Based Workflow Services. 111-128 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2940&spage=111 2003 conf/selmas/2003 SELMAS db/conf/selmas/selmas2003.html#BlakeG03