Carlos Renato Vázquez Antonio Ramírez Laura Recalde Manuel Silva On Controllability of Timed Continuous Petri Nets. 528-541 2008 HSCC http://dx.doi.org/10.1007/978-3-540-78929-1_38 conf/hybrid/2008 db/conf/hybrid/hscc2008.html#VazquezRRS08