1. Best,E.: Some Classes of Live and Safe Petri Nets, in K.Voss, H.J.Genrich, G.Rozenberg: ”Concurrency and Nets, Advances of Petri Nets”, Springer, Berlin 1887.
2. Esparza,J.: Minimal Deadlocks in Free Choice Nets, Hildesheimer Informatikberichte 1/89, Institut für Informatik, Universität Hildesheim
3. Esparza,J.: Synthesis Rules for Petri Nets, and How They Lead to New Results, Hildesheimer Informatikberichte 5/90, Institut für Informatik, Universität Hildesheim.
4. Esparza,J.;Silva,M.: A Polynomial-Time Algorithm to Decide Liveness of Bounded Free Choice Nets, Hildesheimer Informatikberichte 12/90, Institut für Informatik, Universität Hildesheim.
5. Hack,M.H.T.: Analysis of Production Schemata by Petri Nets, TR-94, MIT, Boston 1972 corrected june 1974