Nanette Bauer Sebastian Engell Ralf Huuck Sven Lohmann Ben Lukoschus Manuel Remelhe Olaf Stursberg Verification of PLC Programs Given as Sequential Function Charts. 517-540 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3147&spage=517 2004 conf/dfg/2004 SoftSpez Final Report db/conf/dfg/softspez2004.html#BauerEHLLRS04