Padberg, J.; Kreowski, H.-J.
        
        Loose Semantics of Petri Nets
        In: Kreowski, H.-J.; Montanari, U.; Orejas, F.; Rozenberg, G. (eds.): Formal Methods in Software and Systems Modeling. Springer, Berlin Heidelberg. 2005, pp. 370-384
        
        (Workgroup: 
Theoretical Computer Science)