Francesc Esteva Lluis Godo Carles Noguera Expanding the propositional logic of a t-norm with truth-constants: completeness results for rational semantics. 273-284 2010 14 Soft Comput. 3 http://dx.doi.org/10.1007/s00500-009-0402-8 db/journals/soco/soco14.html#EstevaGN10