An Alternative Way to Analyze Workflow Graphs. - Wil M. P. van der Aalst; Alexander Hirnschall; H. M. W. Verbeek (CAiSE, 2002)

XRL/Flower: Supporting Inter-organizational Workflows Using XML/Petri-Net Technology. - H. M. W. Verbeek; Alexander Hirnschall; Wil M. P. van der Aalst (WES, 2002)