Patricia Johann Janis Voigtländer The Impact of seq on Free Theorems-Based Program Transformations. 63-102 2006 69 Fundam. Inform. 1-2 http://iospress.metapress.com/openurl.asp?genre=article&issn=0169-2968&volume=69&issue=1&spage=63 db/journals/fuin/fuin69.html#JohannV06