1. The Java Programming Language;Arnold,1996
2. Back, R.J.R., Procedural Abstraction in the Refinement Calculus, Technical report, Department of Computer Science, Abo - Finland (1987)
3. A weakest precondition semantics for refinement of object-oriented programs;Cavalcanti;IEEE Transactions on Software Engineering,2000
4. A weakest precondition semantics for an object-oriented language of refinement;Cavalcanti,1999
5. An Inconsistency in Procedures, Parameters and Substitution in the Refinement Calculus;Cavalcanti;Science of Computer Programming,1999