[2] G. Birkhoff: 
Lattice Theory, 3rd ed. AMS Colloq. Publ., vol. XXV. Providence, Rhode Island, 1967. 
MR 0227053 
[5] C. C. Chang: 
A new proof of completeness of the Łukasiewicz axioms. Trans. Amer. Math. Soc. 93 (1959), 74–90. 
MR 0122718 
[6] R. Cignoli, I. M. L. D’Ottaviano and D. Mundici: 
Algebraic Foundations of Many-valued Reasoning. Kluwer, Dordrecht, 1999. 
MR 1786097 
[7] R. Cignoli, F. Esteva, L. Godo and A. Torrens: 
Basic fuzzy logic is the logic of continuous $t$-norms and their residua. Soft Computing 4 (2000), 106–112. 
DOI 10.1007/s005000000044 
[8] B. Csákány: 
Characterizations of regular varieties. Acta Sci. Math. (Szeged) 31 (1970), 187–189. 
MR 0272697 
[10] K. Fichtner: 
Eine Bemerkung über Mannigfaltigkeiten universeller Algebren mit Idealen. Monatsb. Deutsch. Akad. Wiss. Berlin 12 (1970), 21–25. 
MR 0256968 | 
Zbl 0198.33601 
[11] J. Font, A. Rodriguez and A. Torrens: 
Wajsberg algebras. Stochastica 8 (1984), 5–31. 
MR 0780136 
[13] G. Grätzer: Two Mal’cev-type theorems in universal algebra. J. Comb. Theory 8 (1970), 334–342.
[14] P. Hájek: 
Metamathematics of Fuzzy Logic. Kluwer, Dordrecht, 1998. 
MR 1900263 
[15] U. Höhle: Commutative residuated monoids. In: Non-classical logics and their applications to fuzzy subsets, U. Höhle, E. P. Klement (eds.), Kluwer, Dordrecht, 1995.
[17] B. Jónsson: On the representation of lattices. Math. Scand. 2 (1953), 295–314.
[18] A. I. Mal’cev: On the general theory of algebraic systems. Matem. Sbornik 35 (1954), 3–20. (Russian)
[19] V. Novák, I. Perfilieva and J. Močkoř: 
Mathematical Principles of Fuzzy Logic. Kluwer, Dordrecht, 1999. 
MR 1733839 
[20] J. Pavelka: 
On fuzzy logic  I, II, III. Zeit. Math. Log. Grungl. Math. 25 (1979), 45–52, 119–134, 447–464. 
MR 0524558 
[22] R. Wille: 
Kongruenzklassengeometrien. Lecture Notes in Math. Springer-Verlag, Berlin-Heidelberg-New York, 1970. 
MR 0262149