1. Universal Algebra;Cohn,1965
2. An Initial Algebra Approach to the Specification, Correctness, and Implementation of Abstract Data Types;Goguen,1978
3. Universal Algebra;Gratzer,1979
4. Algebraic Structure Theory of Sequential Mechines;Hartmanis,1966
5. Introduction to Automata Theory, Languages, and Computation;Hopcroft,1979