18864 Robert Clariso'/Enrico Rodrigues Carbonell/Jordi Cortadella:
Derivation of non-structural invariants of Petri nets using abstract
interpretation. Springer LN CS 3536 (2005), 188-207.

10389 Karsten Schmidt: On the computation of place invariants for
algebraic Petri nets. Internet ca. 1992, 18p.

10395 Karsten Schmidt: T-invariants of algebraic Petri nets.
Internet 1994, 41p.

10387 Karsten Schmidt: Computations of invariants for algebraic
Petri nets. Internet 1994, 23p.

18767 Katja Winder: Invariantenbasierte Strukturierung von Petrinetzen.
Diplomarbeit TU Cottbus 2006, 89p.