Nick Russell Arthur H. M. ter Hofstede newYAWL: Towards Workflow 2.0. 79-97 2009 2 T. Petri Nets and Other Models of Concurrency http://dx.doi.org/10.1007/978-3-642-00899-3_5 journals/topnoc/2009-2 db/journals/topnoc/topnoc2.html#RussellH09