1. Burstall, R.M.; Goguen, J.A. The semantics of Clear, a specification language, Proc. Copenhagen Winter School on Abstract Software Specification, Springer LNCS 86, pp. 292–332, 1980.
2. Clerici, S.; Orejas, F. GSBL: an algebraic specification language based on inheritance, Proc. Europ. Conf. on Object Oriented Programming, (Oslo, 1988), Springer LNCS.
3. Ehrig, H. A categorical concept of constraints for algebraic specifications, Proc. Int. Workshop on Categorical Methods in Computer Science with Aspects from Topology, Springer LNCS 332, (1989).
4. Ehrig, H., Mahr, B.Fundamentals of algebraic specification 1, EATCS Monographs on Theor. Comp. Sc., Springer Verlag, 1985.
5. Ehrig, H., Pepper, P., Orejas, F. On recent trends in algebraic specification, Proc. ICALP 89, Springer LNCS 372, (1989), 263–289.