Naiqi Wu MengChu Zhou ZhiWu Li Resource-Oriented Petri Net for Deadlock Avoidance in Flexible Assembly Systems. 56-69 2008 38 IEEE Transactions on Systems, Man, and Cybernetics, Part A 1 http://dx.doi.org/10.1109/TSMCA.2007.909542 db/journals/tsmc/tsmca38.html#WuZL08