1. Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., Walter, P.: The Molecular Biology of The Cell, 4th edn. Garland Publ. Inc., London (2002)
2. Bernardini, F., Gheorghe, M.: On the Power of Minimal Symport/Antiport. In: Alhazov, A., Martin-Vide, C., Păun, Gh. (eds.): Workshop on Membrane Computing, WMC-2003, Tarragona, July 17–22, Technical Report N. 28/03, Research Group on Mathematical Linguistics, Universitat Rovira i Virgili, Tarragona, pp. 72–83 (2003)
3. Lecture Notes in Computer Science;R. Freund,2003
4. Lecture Notes in Computer Science;P. Frisco,2003
5. Hopcroft, J., Ulmann, J.: Introduction to Automata Theory, Languages, and Computation. Addison-Wesley, Reading (1979)