Alhazov, A., Freund R., Ivanov S., & Pérez-Jiménez M. J.  (2019).??P Systems: From anti-matter to anti-rules.  Seventeenth Brainstorming Week on Membrane Computing.  41-58.

Freund, R., Pérez-Hurtado I., Riscos-Núñez A., & Verlan S.  (2013).??A formalization of membrane systems with dynamically evolving structures.  International Journal of Computer Mathematics. 90(4),?801-815.

Freund, R., Pérez-Hurtado I., Riscos-Núñez A., & Verlan S.  (2012).??A formal framework for P systems with dynamic structure.  13th International Conference on Membrane Computing (CMC13).  199-210.

Freund, R., Pérez-Hurtado I., Riscos-Núñez A., & Verlan S.  (2012).??A Formal Framework for P Systems with Dynamic Structure.  Tenth Brainstorming Week on Membrane Computing. I, 111-122.

Freund, R., Gheorghe M., Marcus S., Mitrana V., & Pérez-Jiménez M. J.  (2011).??Special Issue-Natural Computing: Theory and applications. Preface.  International Journal of Foundations of Computer Science. 22(1),?1-6.

Freund, R., Kogler M., Paun G., & Pérez-Jiménez M. J.  (2009).?? Analele Universitatii din Bucuresti. Seria Informatica.  Analele Universitatii din Bucuresti. Seria Informatica.  1-22.

Murphy, N., & Woods D.  (2008).??A characterisation of NL using membrane systems without charges and dissolution.  (Cristian Calude, José F. Costa, Rudolf Freund, Marion Oswald, Grzegorz Rozenberg, Ed.).Unconventional Computation, UC'08. 5204, 164-176.

Rivero-Gil, E., Gutiérrez-Naranjo M. A., Romero-Jiménez Á., & Riscos-Núñez A.  (2008).??A Software Tool for Generating Graphics by Means of P Systems.  (Erzsebet Csuhaj-Varjú, Rudolf Freund, Marion Oswald, Kai Salomaa, Ed.).International Workshop on Computing with Biomolecules.  87-100.

Chen, H., Freund R., Ionescu M., Paun G., & Pérez-Jiménez M. J.  (2007).??On string languages generated by Spiking Neural P systems .  Fundamenta Informaticae. 75(1-4),?141-162.

Freund, R., Paun G., & Pérez-Jiménez M. J.  (2007).??Polarizationless P systems with active membranes working in the minimally parallel mode.  Lecture Notes in Computer Science. 4618, 62-76.

Besozzi, D., Busi N., Franco G., Freund R., & Paun G.  (2006).??Two Universality Results for (Mem)brane Systems.  (Miguel A. Gutiérrez-Naranjo, Ed.).Fourth Brainstorming Week on Membrane Computing . I, 49-62.

Chen, H., Freund R., Ionescu M., Paun G., & Pérez-Jiménez M. J.  (2006).??On String Languages Generated by Spiking Neural P systems .  Fourth Brainstorming Week on Membrane Computing . I, 169-193.

Cavaliere, M., Freund R., Leistch A., & Paun G.  (2006).??Event-related outputs of computations in P systems.  Journal of Automata, Languages and Combinatorics. 11(3),?263-278.

Freund, R., Paun G., Rozenberg G., & Salomaa A.  (2006).??Membrane Computing (6th International Workshop, WMC 2005, Revised Selected and Invited Papers).  Lecture Notes in Computer Science. 3850 , 

Alhazov, A., Freund R., & Riscos-Núñez A.  (2006).??Membrane division, Restricted Membrane Creation and Object Complexity in  P Systems.  International Journal of Computer Mathematics. 83, 529-547.

Freund, R., Lojka G., Oswald M., & Paun G.  (2005).??Pre-proceedings of the Sixth International Workshop on Membrane Computing, WMC6 .  Workshop on Membrane Computing, WMC6.  VII+539.

Cavaliere, M., Freund R., Leistch A., & Paun G.  (2005).??Event-related outputs of computations in P systems.  (Miguel A. Gutiérrez-Naranjo, Agustín Riscos-Núñez, Francisco J. Romero-Campero, Dragos Sburlan, Ed.).Third Brainstorming Week on Membrane Computing.  107-122.

Freund, R., Ibarra O., Paun G., & Yen H. C.  (2005).??Matrix Languages, Register Machines, Vector Addition Systems.  (M. A. Gutiérrez Naranjo, Agustín Riscos-Núñez, Francisco J. Romero-Campero, Dragos Sburlan, Ed.).Third Brainstorming Week on Membrane Computing.  155-167.

Alhazov, A., Freund R., & Paun G.  (2005).??Computational Completeness of P Systems with Active Membranes and Two Polarizations.  Lecture Notes in Computer Science. 3354, 82-92.

Alhazov, A., Freund R., & Riscos-Núñez A.  (2005).??One and Two Polarizations, Membrane Creation and Objects Complexity in P Systems.  TAPS'05 Workshop on Theory and Application of Systems.  9-18 .

Freund, R., Paun G., & Pérez-Jiménez M. J.  (2005).??Tissue-like P systems with channel-states.  Theoretical Computer Science. 330(1),?101-116.

Freund, R., Martín-Vide C., & Paun G.  (2004).??From regulated rewriting to computing with membranes: collapsing hierarchies.  Theoretical Computer Science. 312(2-3),?143 - 188   .

Kelemene, J., Freund R., & Paun G.  (2003).??A Note on Emergence in Multi-Agent String Processing Systems.  Computing and Informatics. 22(6),?623-637.