Mogens Nielsen Dan Simpson Application and Theory of Petri Nets 2000, 21st International Conference, ICATPN 2000, Aarhus, Denmark, June 26-30, 2000, Proceeding ICATPN Lecture Notes in Computer Science 1825 Springer 2000 3-540-67693-7 db/conf/apn/icatpn2000.html