Grigori Mints Ting Zhang A proof of topological completeness for <i>S</i>4 in (0, 1). 231-245 2005 133 Ann. Pure Appl. Logic 1-3 http://dx.doi.org/10.1016/j.apal.2004.10.010 db/journals/apal/apal133.html#MintsZ05