@article {2103, title = {An efficient time-free solution to QSAT problem using P systems with proteins on membranes}, journal = {Information and Computation}, volume = {2560}, year = {2017}, pages = {287-299}, doi = {http://dx.doi.org/10.1016/j.ic.2017.06.005}, author = {Bosheng Song and Mario J. P{\'e}rez-Jim{\'e}nez and Linqiang Pan} }