Francesco Bernardini Marian Gheorghe Maurice Margenstern Sergey Verlan How to Synchronize the Activity of All Components of a P System? 1183-1198 2008 19 Int. J. Found. Comput. Sci. 5 http://dx.doi.org/10.1142/S0129054108006224 db/journals/ijfcs/ijfcs19.html#BernardiniGMV08