@incollection{Petri_1980,
    doi = {10.1007/3-540-10001-6_21},
    url = {https://doi.org/10.1007%2F3-540-10001-6_21},
    year = {1980},
    publisher = {Springer Berlin Heidelberg},
    pages = {1--19},
    author = {C. A. Petri},
    title = {Introduction to general net theory},
    booktitle = {Net Theory and Applications}
}

@incollection{Petri_1980, doi = {10.1007/3-540-10001-6_21}, url = {https://doi.org/10.1007%2F3-540-10001-6_21}, year = {1980}, publisher = {Springer Berlin Heidelberg}, pages = {1--19}, author = {C. A. Petri}, title = {Introduction to general net theory}, booktitle = {Net Theory and Applications} }