1. Computability and Unsolvability;Davis,1958
2. Automata in general algebras;Eilenberg;Information and Control,1967
3. Algebraic theories and program schemes;Calvin Elgot,1971
4. Enumerability, Decidability, Computability;Hermes,1965
5. Functorial semantics of algebraic theories;William Lawvere;Proceedings of the National Acedemy of Sciences,1963