Shankara Narayanan Krishna Gabriel Ciobanu A S<sub>2</sub><sup><i>P</i></sup> ÈP<sub>2</sub><sup><i>P</i></sup>\Sigma_2^P \cup \Pi_2^P Lower Bound Using Mobile Membranes. 275-288 2011 DCFS http://dx.doi.org/10.1007/978-3-642-22600-7_22 conf/dcfs/2011 db/conf/dcfs/dcfs2011.html#KrishnaC11