Traian Serbanuta Gheorghe Stefanescu Grigore Rosu Defining and Executing P Systems with Structured Data in K. 374-393 2008 Workshop on Membrane Computing http://dx.doi.org/10.1007/978-3-540-95885-7_26 conf/membrane/2008 db/conf/membrane/membrane2008.html#SerbanutaSR08