Torsten Priebe Björn Muschall Wolfgang Dobmeier Günther Pernul A Flexible Security System for Enterprise and e-Government Portals. 884-893 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3180&spage=884 2004 conf/dexa/2004 DEXA db/conf/dexa/dexa2004.html#PriebeMDP04