Daniela Besozzi Claudio Zandron Giancarlo Mauri Nicoletta Sabadini P Systems with Gemmation of Mobile Membranes. 136-153 2001 conf/ictcs/2001 ICTCS http://link.springer.de/link/service/series/0558/bibs/2202/22020136.htm db/conf/ictcs/ictcs2001.html#BesozziZMS01