Panagiotis Chountas Ilias Petrounias Vassilis Kodogiannis Temporal Modelling in Flexible Workflows. 123-130 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2869&spage=123 2003 conf/iscis/2003 ISCIS db/conf/iscis/iscis2003.html#ChountasPK03