1. A Course in Universal Algebra;Burris,1981
2. Universal varieties of (0,1)-lattices;Goralc̆ı́k;Canad. J. Math.,1990
3. Cylindric Algebras, Part I;Henkin,1971
4. H. Herrlich, On the concept of reflections in general topology, Proceedings of the Symposium on Extension Theory of Topological Structures, Berlin 1967.
5. Finite-to-finite universal varieties of distributive double p-algebras;Koubek;Comment. Math. Univ. Carolin.,1990