C. Bui-thanh, H. Klaudel, and F. Pommereau, Petri nets with causal time for system verification, Electronic Notes in Theoretical Computer Science, vol.68, issue.5, 2002.
DOI : 10.1016/S1571-0661(04)80521-8
URL : https://hal.archives-ouvertes.fr/hal-00114682

R. Durchholz, Causality, time, and deadlines, Data & Knowledge Engineering, vol.6, issue.6, 1991.
DOI : 10.1016/0169-023X(91)90024-R

F. Pommereau, Causal Time Calculus, FORMATS'03
DOI : 10.1007/978-3-540-40903-8_21
URL : https://hal.archives-ouvertes.fr/hal-00114673

G. Richter, Counting interfaces for discrete time modelling, 1998.