1. R. J. R. Back. On the Correctness of Refinement Steps in Program Development. PhD thesis, Department of Computer Science, University of Helsinki, Helsinki, 1978. Report A-1978–4.
2. R. J. R. Back. Correctness Preserving Program Refinements: Proof Theory and Applications, volume 131 of Mathematical Center Tracts. Mathematical Centre, Amsterdam, 1980.
3. R. J. R. Back. A calculus of refinements for program derivations. Acta Informatica, 25: 593–624, 1988.
4. R. J. R. Back and J. von Wright. Refinement concepts formalized in higher order logic. Reports on computer science and mathematics 85, Abo Akademi, 1989.
5. R. J. R. Back and J. von Wright. Refinement concepts formalized in higher order logic. In IFIP TC2 Working Conference, Sea of Galilei, Israel, 1990.