@inbook{BUT191505,
  author="Milan {Urbášek}",
  title="Categories of Petri nets: a bisimulation approach",
  booktitle="Sborník prací studentů a doktorandů FEI VUT",
  year="1999",
  publisher="unknown",
  address="Brno",
  pages="109--110",
  isbn="80-214-1155-4"
}