Roberto Cignoli Francesc Esteva Lluis Godo On Lukasiewicz Logic with Truth Constants. 869-875 2007 IFSA (2) http://dx.doi.org/10.1007/978-3-540-72434-6_88 conf/ifsa/2007-2 db/conf/ifsa/ifsa2007-2.html#CignoliEG07