R. Freund, Y. Rogozhin, S. Verlan:
"Generating and accepting P systems with minimal left and right insertion and deletion";
in: "Natural Computing - An international Journal", J. Ferrandez et al. (ed.); Springer, 2014, ISSN: 1567-7818, 257 - 268.
http://dx.doi.org/10.1007/s11047-013-9396-3