@proceedings {2175, title = {Counting Membrane Systems}, journal = {Eighteenth International Conference on Membrane Computing (CMC18)}, year = {2017}, pages = {359-372}, author = {Luis Valencia-Cabrera and David Orellana-Mart{\'\i}n and Agust{\'\i}n Riscos-N{\'u}{\~n}ez and Mario J. P{\'e}rez-Jim{\'e}nez} }