1. Lecture Notes in Computer Science;M.A. Bednarczyk,1999
2. Lecture Notes in Computer Science;J. Desel,1991
3. Desel, J., Merceron, A.: Vicinity Rrespecting Homomorphisms for Abstracting System Requirements, Bericht 337., Karlsruhe (1996)
4. Lecture Notes in Computer Science;R. Devillers,1997
5. Fehling, R.: A Concept of Hierarchical Petri nets with Building Blocks. In: The 12th International Conference on Application and Theory of Petri Nets, Gjern, Denmark, June 1991, pp. 370–389 (1991)