Berndt Farwer Saraswati Kalvala Kundan Misra Controller Synthesis for Object Petri Nets. 432-451 http://dx.doi.org/10.1007/978-3-540-39893-6_25 2003 conf/icfem/2003 ICFEM db/conf/icfem/icfem2003.html#FarwerKM03