Nieves R. Brisaboa Agustin González Héctor J. Hernández José R. Paramá The Chase of Datalog Programs. 165-166 http://dx.doi.org/10.1007/BFb0053479 1998 conf/bncod/1998 BNCOD db/conf/bncod/bncod98.html#BrisaboaGHP98