1. Cook, S., Daniels, J.: Designing Object Systems. Object-Oriented Modeling with Syntropy. Prentice Hall, Englewood Cliffs (1994)
2. Lecture Notes in Computer Science;D. Costal,1997
3. Costal, D., Sancho, M.R., Olivé, A., Barceló, M., Costa, P., Quer, C., Roselló, A.: The Cause-Effect Rules of Roses. In: First East-European Symposium on Advances in Databases and Information Systems (ADBIS 1997), St. Petersburg, Russia (September 1997)
4. Gustafsson, M.R., Karlsson, T., Bubenko, J.A.: A Declarative Approach to Conceptual Information Modeling. Information Systems Design Methodologies: A Comparative Review, North-Holland. 93–142
5. Martin, J., Odell, J.J.: Object-oriented Methods: A Foundation. Prentice Hall, Englewood Cliffs (1995)