Dulce Domingos António Rito Silva Pedro Veiga Authorization and Access Control in Adaptive Workflows. 23-38 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2808&spage=23 2003 conf/esorics/2003 ESORICS db/conf/esorics/esorics2003.html#DomingosRV03