L. Schröder, и T. Mossakowski. Journal of Logic and Computation, 14 (4):
571--619(2004)Earlier version appeared in Martin Wirsing, Dirk Pattinson, and Rolf Hennicker (eds.), Recent Trends in Algebraic Development Techniques, 16th International Workshop (WADT 2002), LNCS vol. 2755, Springer, Berlin, 2003, pp. 425-441.