1. Active symbols in pure systems;Bensch;Fundam. Inform.,2007
2. On the degree of nondeterminism;Bordihn,1994
3. A note on the degree of nondeterminism;Bordihn,1994
4. H. Bordihn, H. Fernau, The degree of parallelism, in: C. Mereghetti, B. Palano, G. Pighizzini, D. Wotschke (Eds.), Descriptional Complexity of Formal Systems 7th Workshop DCFS 2005, Universita di Milano, Dipartimento di Informatica e Comunicazione, Rapporto Tecnico 06-05, 2005, pp. 51–62.
5. On the number of active symbols in L and CD grammar systems;Bordihn;J. Automata Lang. Combinatorics,2001