Wlodzimierz Drabent Jakob Henriksson Jan Maluszynski Hybrid Reasoning with Rules and Constraints under Well-Founded Semantics. 348-357 2007 conf/rr/2007 RR http://dx.doi.org/10.1007/978-3-540-72982-2_29 db/conf/rr/rr2007.html#DrabentHM07