1. A large literature on probabilistic process algebras from 1990 or before
2. A series of meetings between Oxford and Manchester over the general principles of data refinement (reification) and its completeness, Participants included Jifeng He, Tony Hoare, Cliff Jones, Peter Lupton, Carroll Morgan, Tobias Nipkow, Ken Robinson, Bill Roscoe, Jeff Sanders, Ib Sørensen and Mike Spivey (1986)
3. Back, R.-J.R.: On the correctness of refinement steps in program development. Report A-1978-4, Dept. Comp. Sci., Univ. Helsinki (1978)
4. Back, R.-J.R.: Data refinement in the refinement calculus. In: Proceedings 22nd Hawaii International Conference of System Sciences, Kailua-Kona (January 1989)
5. Back, R.-J.R., von Wright, J.: Refinement Calculus: A Systematic Introduction. Springer, Heidelberg (1998)