The Isomorphism Problem for Planar 3-Connected Graphs is in Unambiguous Logspace.

Thomas Thierauf Fabian Wagner The Isomorphism Problem for Planar 3-Connected Graphs is in Unambiguous Logspace. 2008 STACS 633-644 http://drops.dagstuhl.de/opus/volltexte/2008/1327 conf/stacs/2008 db/conf/stacs/stacs2008.html#ThieraufW08