1. Calude, C. S., Păun, Gh.: Computing with Cells and Atoms (Chapter 3: “Computing with Membranes”). Taylor & Francis, London (2001)
2. Dassow, J., Păun, Gh.: Regulated Rewriting in Formal Language Theory. Springer-Verlag, Berlin (1989)
3. Dassow, J., Păun, Gh.: On the Power of Membrane Computing. Journal of Universal Computer Science 5, 2 (1999) 33–49 ( http://www.iicm.edu/jucs )
4. Freund, R., Freund, F.: Molecular computing with generalized homogeneous P systems. In: Condon, A., Rozenberg, G. (eds.): Proc. Conf. DNA6, Leiden (2000) 113–125
5. Freund, R., Păun, Gh.: On the Number of Non-terminals in Graph-controlled, Programmed, and Matrix Grammars. In: Margenstern, M., Rogozhin, Y. (eds.): Proc. Conf. Universal Machines and Computations, Chişinău (2001). Springer-Verlag, Berlin (2001)