R. Freund, A. Alhazov, S. Ivanov:
"Variants of P systems with activation and blocking of rules";
Natural Computing, 18 (2019), 3; 593 - 608.
http://dx.doi.org/10.1007/s11047-019-09747-5Electronic version of the publication:
https://publik.tuwien.ac.at/files/publik_285358.pdf