Vincenzo Manca Luca Bianco Federico Fontana Evolution and Oscillation in P Systems: Applications to Biological Phenomena. 63-84 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3365&spage=63 2004 conf/membrane/2004 Workshop on Membrane Computing db/conf/membrane/membrane2004.html#MancaBF04