MONK, Donald. On Equational Classes of Algebraic Versions of Logic I. Mathematica Scandinavica, Berkeley, CA, United States, v. 27, p. 53–71, 1970. DOI: 10.7146/math.scand.a-10987. Disponível em: https://journals.msp.org/mscand/article/view/2340. Acesso em: 25 jul. 2026.