1. Algebraic and Automata-Theoretic Properties of Formal Languages;Ginsburg,1975
2. Remarks on blind and partially blind one-way multicounter machines;Greibach;Theoret. Comput. Sci.,1978
3. On the hierarchy of Petri net languages;Jantzen;R.A.I.R.O. — Informatique Théorique,1979
4. Eigenschaften von Petrinetzsprachen;Jantzen,1979
5. On zerotesting — bounded multicounter machines;Jantzen,1979