@InProceedings {csv.st93,
    author = {S. Castano and P. Samarati and C. Villa},
    booktitle = {Proc. of the IEEE 27th Int. Carnahan Conf. on Security Technology},
    title = {Verifying System Security Using Petri Nets},
    address = {Ottawa, Canada},
    pages = {244-250},
    month = {October},
    year = {1993}
}