Klaus Madlener Birgit Reinert Relating Rewriting Techniques on Monoids and Rings: Congruences on Monoids and Ideals in Monoid Rings. 3-31 1998 208 Theor. Comput. Sci. 1-2 db/journals/tcs/tcs208.html#MadlenerR98 http://dx.doi.org/10.1016/S0304-3975(98)00077-2