1. J. Bergstra and L. Feijs, editors. Algebraic Methods II: Theory, Tools and Applications. Springer-Verlag, 1991. LNCS 490.
2. J. Bergstra, J. Heering, and P. Klint. Module Algebra. J. ACM, 37(2):335–372, Apr. 1990.
3. M. Broy and M. Wirsing. Partial abstract types. Acta Informatica, 18(1):47–64, 1982. Springer-Verlag, Berlin Heidelberg New York.
4. L. Feijs, H. Jonkers, C. Koymans, and G. Renardel de Lavalette. Formal Definition of the Design Language COLD-K. Technical Report METEOR/t7/PRLE/7, Philips Research Laboratories (PRLE), P.O. Box 80.000, 5600 JA Eindhoven, the Netherlands, Apr. 1987. ESPRIT project 432.
5. G. Grätzer. Universal Algebra. D. van Nostrand Company, Inc., 1968.