.PULIAFITO, A., M. Scarpa, and K..S.TRIVEDI,  "Petri nets with k simultaneously enabled generally distributed timedtransitions",  PERFORMANCE EVALUATION, vol. 32, 1998.

.BOBBIO, A., A..PULIAFITO, M. Scarpa, and M..TELEK,  "Time domain analysis of Markov regenerative processes",  8th European Simulation Symposium, pp. 187?191, 26, 1996.

.CATANIA, V., A..PULIAFITO, M. Scarpa, and L..VITA,  "Concurrent Generalized Petri Nets",  Computations with Markov Chains, Amsterdam, Kluwer Academic Publishers, pp. 359?382, 18 January, 1995.