Joachim Wehler. Simplified proof of the blocking theorem for free-choice Petri nets. J. Comput. Syst. Sci., 76(7):532-537, 2010. [doi]
@article{Wehler10-0, title = {Simplified proof of the blocking theorem for free-choice Petri nets}, author = {Joachim Wehler}, year = {2010}, doi = {10.1016/j.jcss.2009.10.001}, url = {http://dx.doi.org/10.1016/j.jcss.2009.10.001}, researchr = {https://researchr.org/publication/Wehler10-0}, cites = {0}, citedby = {0}, journal = {J. Comput. Syst. Sci.}, volume = {76}, number = {7}, pages = {532-537}, }