1. Alhazov, A., Freund, R., Oswald, M., Verlan, S.: Partial versus total halting in P systems. In: Gutiérrez-Naranjo, M.A., Păun, G., Romero-Jiménez, A., Riscos-Núñez, A. (eds.) Proc. Fifth Brainstorming Week on Membrane Computing, Sevilla, pp. 1–20 (2007)
2. Andrei, O., Ciobanu, G., Lucanu, D.: A rewriting logic framework for operational semantics of membrane systems. Theoretical Computer Science 373(3), 163–181 (2007)
3. Bernardini, F., Gheorghe, M., Margenstern, M., Verlan, S.: Networks of Cells and Petri Nets. In: Gutiérrez-Naranjo, M.A., Păun, G., Romero-Jiménez, A., Riscos-Núñez, A. (eds.) Proc. Fifth Brainstorming Week on Membrane Computing, Sevilla, pp. 33–62 (2007)
4. Ciobanu, G., Andrei, O., Lucanu, D.: Structural operational semantics of P systems. In: [9], 1–23
5. Ciobanu, G., Pan, L., Păun, G., Pérez-Jiménez, M.J.: P systems with minimal parallelism. Theoretical Computer Science 378(1), 117–130 (2007)