Jan Hidders Natalia Kwasnikowska Jacek Sroka Jerzy Tyszkiewicz Jan Van den Bussche Petri Net + Nested Relational Calculus = Dataflow. 220-237 2005 conf/otm/2005-3 OTM Conferences (1) http://dx.doi.org/10.1007/11575771_16 db/conf/otm/otm2005-1c.html#HiddersKSTB05