@incollection{Esparza_1995,
    doi = {10.1007/3-540-60249-6_54},
    url = {https://doi.org/10.1007%2F3-540-60249-6_54},
    year = {1995},
    publisher = {Springer Berlin Heidelberg},
    pages = {221--232},
    author = {Javier Esparza},
    title = {Petri nets, commutative context-free grammars, and basic parallel processes},
    booktitle = {Fundamentals of Computation Theory}
}

@incollection{Esparza_1995, doi = {10.1007/3-540-60249-6_54}, url = {https://doi.org/10.1007%2F3-540-60249-6_54}, year = {1995}, publisher = {Springer Berlin Heidelberg}, pages = {221--232}, author = {Javier Esparza}, title = {Petri nets, commutative context-free grammars, and basic parallel processes}, booktitle = {Fundamentals of Computation Theory} }