Arne Meier Martin Mundhenk Thomas Schneider Michael Thomas Volker Weber Felix Weiss The Complexity of Satisfiability for Fragments of Hybrid Logic-Part I. 587-599 2009 MFCS http://dx.doi.org/10.1007/978-3-642-03816-7_50 conf/mfcs/2009 db/conf/mfcs/mfcs2009.html#MeierMSTWW09