Philippe Bidinger Jean-Bernard Stefani The Kell Calculus: Operational Semantics and Type System. 109-123 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2884&spage=109 2003 conf/fmoods/2003 FMOODS db/conf/fmoods/fmoods2003.html#BidingerS03