1. ADJ (J. Goguen, J. Thatcher, E. Wagner) (1976) An Initial Algebra Approach to the Specification, Correctness, and Implementation of Abstract Data Types, IBM Research Report RC 6487.
2. ADJ (J. Goguen, J. Thatcher, E. Wagner, J. Wright) (1977) Initial Algebra Semantics and Continuous Algebras, Jour. ACM 24, 68–95.
3. Boyer, R. and J Moore. (1975): Proving Theorems about LISP Functions, Jour. ACM 22(1), 129–144 (January).
4. Cartwright, R. (1976): User-Defined Data Types as Aid to Verifying LISP Programs, in S. Michaelson and R. Milner (eds.), Automata Languages, and Programming, pp. 228–256, Edinburgh Press, Edinburgh.
5. Cartwright, R. (1980): A Constructive Alternative to Axiomatic Data Type Definitions. Proc. of 1980 LISP Conference, Stanford, California, August, 1980, pp. 46–55.