1. Abrial, J.-R.: The B-Book. Cambridge University Press, Cambridge (1996)
2. Back, R.J., von Wright, J.: Refinement Calculus: A Systematic Introduction. Springer, New York (1998)
3. Barr, M., Wells, C.: Category Theory for Computer Science. Centre de Recherches Mathématiques, Université de Montréal, Montreal (1999)
4. Bird, R., de Moor, O.: Algebra of Programming. Prentice-Hall, Upper Saddle River (1997)
5. Basic Category Theory, Encyclopedia of Mathematics and its Applications;F Borceux,1994