Matthias Jantzen.
On the hierarchy of Petri net languages.
R.A.I.R.O. Informatique théorique/Theoretical Informatics,
13(1):19-30, 1979.
@article{Jantzen79,
Author = {Jantzen, Matthias},
Journal = {R.A.I.R.O. Informatique th{\'e}orique/Theoretical Informatics},
Number = 1,
Pages = {19--30},
Title = {On the hierarchy of {Petri} net languages},
Volume = 13,
Year = 1979
}