1. Abadi, M., and L. Cardelli, A Theory of Objects. Springer-Verlag, 1996.
2. Adamek J.: An introduction to coalgebra. Theory and Applications of Categories 14(8), 157–199 (2005)
3. Barbosa, L. S., J. N. Oliveira, and A. M. Silva, Calculating invariants as coreflexive bisimulations. In J. Meseguer and G. Rosu, (eds.), Algebraic Methodology and Software Technology, 12th International Conference, AMAST 2008, Urbana, IL, USA, July 28-31, 2008, Proceedings Springer Lect. Notes Comp. Sci. (5140), 2008, pp. 83–99.
4. Batory D., J. N. Sarvela, A. Rauschmayer: Scaling step-wise refinement. IEEE Trans. in Sofware Engineering 30(6), 355–371 (2004)
5. Bird R., and O. Moor, The Algebra of Programming. Series in Computer Science. Prentice-Hall International, 1997.