1. Composing Specifications. M. Abadi and L. Lamport. DEC Technical Report 66, October 1990.
2. Abstract Machines, Parts I, II and III. J. R. Abrial. Unpublished, 1990.
3. The B Method. J. R. Abrial, M. K. O. Lee, D. S. Neilson and P. N. Scharbach. VDM '91, Formal Software Development Methods, LNCS 552, Springer-Verlag (1991).
4. Operation Decomposition Proof Obligations for Blocks and Procedures. J. A. Ah-Kee. Ph.D. Thesis. University of Manchester. 1989.
5. A Calculus of Refinements for Program Derivations. R.J.R. Back. Acta Informatica (1988).