Matthias Baaz Norbert Preining Richard Zach Characterization of the Axiomatizable Prenex Fragments of First-Order Gödel Logics. 175-180 2003 conf/ismvl/2003 ISMVL http://computer.org/proceedings/ismvl/1918/19180175abs.htm db/conf/ismvl/ismvl2003.html#BaazPZ03