Alfons Geser Dieter Hofbauer Johannes Waldmann Hans Zantema Finding Finite Automata That Certify Termination of String Rewriting. 134-145 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3317&spage=134 2004 conf/wia/2004 CIAA db/conf/wia/ciaa2004.html#GeserHWZ04