Radha Jagadeesan Alan Jeffrey James Riely A Calculus of Untyped Aspect-Oriented Programs. 54-73 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2743&spage=54 2003 conf/ecoop/2003 ECOOP db/conf/ecoop/ecoop2003.html#JagadeesanJR03