H. Plünnecke. European Workshop on Applications and Theory in Petri Nets, volume 188 of Lecture Notes in Computer Science, page 392-412. Springer, (1984)
S. Drees, D. Gomm, H. Plünnecke, W. Reisig, and R. Walter. European Workshop on Applications and Theory of Petri Nets, volume 266 of Lecture Notes in Computer Science, page 309-451. Springer, (1986)