1. Distributive Lattices;Balbes,1974
2. Notes on equational classes of algebras;Berman,1974
3. A course in Universal Algebra;Burris,1981
4. Boolean Multiplicative closures. I & II;Cignoli;Proc. Japan Acad.,1966
5. Algebraic Logic, I. Monadic Boolean algebras;Halmos;Compositio Math.,1955