Francesca Levi Chiara Bodei A Control Flow Analysis for Safe and Boxed Ambients. 188-203 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2986&spage=188 2004 conf/esop/2004 ESOP db/conf/esop/esop2004.html#LeviB04