1. Correctness Preserving Program Refinements: Proof Theory and Applications;Back,1980
2. On the notion of correct refinement of programs;Back,1979
3. Mathematical Theory of Program Correctness;de Bakker,1980
4. Systematics of transformation rules;Bauer,1979
5. Semantics of nondeterministic and noncontinuous constructs;Broy,1979