José Meseguer Ugo Montanari Vladimiro Sassone On the Model of Computation of Place/Transition Petri Nets. 16-38 1994 conf/apn/1994 Application and Theory of Petri Nets db/conf/apn/apn1994.html#MeseguerMS94 http://dx.doi.org/10.1007/3-540-58152-9_3