@inproceedings {1442, title = {On State Estimation of Timed Choice-Free Petri Nets}, booktitle = {18th IFAC World Congress}, year = {2011}, month = {09/2011}, publisher = {IFAC}, organization = {IFAC}, address = {Milan, Italy}, author = {X. Wang and Mahulea, Cristian and J. Julvez and M. Silva} }