Alfons Geser Dieter Hofbauer Johannes Waldmann Hans Zantema On tree automata that certify termination of left-linear term rewriting systems. 512-534 2007 205 Inf. Comput. 4 http://dx.doi.org/10.1016/j.ic.2006.08.007 db/journals/iandc/iandc205.html#GeserHWZ07