1. D. Besozzi, C. Ferretti, G. Mauri, C. Zandron, Parallel Rewriting P Systems with Deadlock, Pre-Proceedings of DNA8 Conference (M. Hagiya, A. Ohuchi, eds.), Hokkaido University, Japan, June 2002, 171–183.
2. J. Dassow, Gh. Păun, Regulated Rewriting in Formal Language Theory, Springer-Verlag, Berlin, 1989.
3. C. Ferretti, G. Mauri, C. Zandron, G. Păun, On Three Variants of Rewriting P Systems, Theoretical Computer Science, to appear.
4. S. N. Krishna, Languages of P systems: Computability and Complexity, PhD Thesis, 2001.
5. S. N. Krishna, R. Rama, A Note on Parallel Rewriting in P Systems, Bulletin of the EATCS, 73 (February 2001), 147–151.