R. Freund, A. Alhazov, S. Ivanov: "Unfair P Systems"; in: "Proceedings of the Workshop on Membrane Computing at UCNC 2018. Fontainebleau, France June 25th, 2018", TU Wien, 2018, 63 - 71.
https://publik.tuwien.ac.at/files/publik_275974.pdf