Norbert Schirmer A Verification Environment for Sequential Imperative Programs in Isabelle/HOL. 398-414 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3452&spage=398 2004 conf/lpar/2004 LPAR db/conf/lpar/lpar2004.html#Schirmer04