Alfons Geser Dieter Hofbauer Johannes Waldmann Match-Bounded String Rewriting Systems. 149-171 2004 15 Appl. Algebra Eng. Commun. Comput. 3-4 http://www.springerlink.com/index/10.1007/s00200-004-0162-8 db/journals/aaecc/aaecc15.html#GeserHW04