Hypergraph systems and their extensions

Janssens, D.; Rozenberg, G.

RAIRO. Informatique théorique, Volume 17 (1983) p. 163-196

On the separating power of EOL systems

Ehrenfeucht, A.; Rozenberg, G.

RAIRO. Informatique théorique, Volume 17 (1983) p. 13-22