[1] P.  Bahls, J.  Cole, N.  Galatos, P.  Jipsen, and C.  Tsinakis: Cancellative residuated lattices. Algebra Universalis 50 (2003), 83–106. DOI 10.1007/s00012-003-1822-4 | MR 2026830

[2] K.  Baker, J.  Wang: Definable principal subcongruences. Algebra Universalis 47 (2002), 145–151. DOI 10.1007/s00012-002-8180-5 | MR 1916612

[3] S.  Burris, H. P.  Sankappanavar: A Course in Universal Algebra. GTM  78. Springer-Verlag, New York-Heidelberg-Berlin, 1981. MR 0648287

[4] K.  Blount, C.  Tsinakis: The structure of residuated lattices. Internat. J.  Algebra Comput. 13 (2003), 437–461. DOI 10.1142/S0218196703001511 | MR 2022118

[5] R. P.  Dilworth, M.  Ward: Residuated lattices. Trans. Amer. Math. Soc. 45 (1939), 335–354. DOI 10.1090/S0002-9947-1939-1501995-3 | MR 1501995

[6] N.  Galatos: Minimal varieties of residuated-lattices. Algebra Universalis 52 (2004), 215–239. DOI 10.1007/s00012-004-1870-4 | MR 2161651 | Zbl 1082.06011

[7] N.  Galatos: Equational bases for joins of residuated-lattice varieties. Studia Logica 76 (2004), 227–240. DOI 10.1023/B:STUD.0000032086.42963.7c | MR 2072984 | Zbl 1068.06007

[8] N.  Galatos: Varieties of residuated lattices. PhD. Thesis, Vanderbilt University, 2003. MR 2704503

[9] J.  Hart, L.  Rafter, and C.  Tsinakis: The structure of commutative residuated lattices. Internat. J.  Algebra Comput. 12 (2002), 509–524. DOI 10.1142/S0218196702001048 | MR 1919685

[10] P.  Jipsen, C.  Tsinakis: A survey of residuated lattices. In: Ordered Algebraic Structures, J.  Martinez (ed.), Kluwer Academic Publishers, Dordrecht, 2002, pp. 19–56. MR 2083033

[11] R.  McKenzie: Equational bases for lattice theories. Math. Scand. 27 (1970), 24–38. DOI 10.7146/math.scand.a-10984 | MR 0274353 | Zbl 0307.08001

[12] R.  McKenzie, G.  McNulty, and W.  Taylor: Algebras, Lattices, Varieties, Vol  I. Wadsworth & Brooks/Cole, Monterey, 1987. MR 0883644