Adam Antonik Michael Huth Kim Guldstrand Larsen Ulrik Nyman Andrzej Wasowski EXPTIME-complete Decision Problems for Modal and Mixed Specifications. 19-33 2009 242 Electr. Notes Theor. Comput. Sci. 1 http://dx.doi.org/10.1016/j.entcs.2009.06.011 db/journals/entcs/entcs242.html#AntonikHLNW09