1. Some undecidable problems about Petri nets;Araki;Trans. IECE 59-D,1976
2. Co-operating sequential processes;Dijkstra,1968
3. Decision problems for Petri nets and vector addition systems;Hack,1974
4. The recursive equivalence of the reachability problem and the liveness problem for Petri nets and vector addition systems;Hack;IEEE 15th Annual Symposium on Switching and Automata Theory,1974
5. Petri net languages;Hack,1975