Vilém Novák Fuzzy algebras as models of fuzzy theories. 43-46 1999 EUSFLAT-ESTYLF Joint Conf. http://www.eusflat.org/publications/proceedings/EUSFLAT-ESTYLF_1999/papers/043-Novak-especial.pdf conf/eusflat/1999 db/conf/eusflat/eusflat1999.html#Novak99