Salvador Lucas José Meseguer Operational Termination of Membership Equational Programs: the Order-Sorted Way. 207-225 2009 238 Electr. Notes Theor. Comput. Sci. 3 http://dx.doi.org/10.1016/j.entcs.2009.05.021 db/journals/entcs/entcs238.html#LucasM09