@article{Valk_1985,
    doi = {10.1007/bf00289715},
    url = {https://doi.org/10.1007%2Fbf00289715},
    year = {1985},
    month = {mar},
    publisher = {Springer Science and Business Media {LLC}},
    volume = {21},
    number = {6},
    pages = {643--674},
    author = {Rüdiger Valk and Matthias Jantzen},
    title = {The residue of vector sets with applications to decidability problems in Petri nets},
    journal = {Acta Informatica}
}

@article{Valk_1985, doi = {10.1007/bf00289715}, url = {https://doi.org/10.1007%2Fbf00289715}, year = {1985}, month = {mar}, publisher = {Springer Science and Business Media {LLC}}, volume = {21}, number = {6}, pages = {643--674}, author = {Rüdiger Valk and Matthias Jantzen}, title = {The residue of vector sets with applications to decidability problems in Petri nets}, journal = {Acta Informatica} }