Raffaella Gentilini Klaus Schneider B. Mishra Successive Abstractions of Hybrid Automata for Monotonic CTL Model Checking. 224-240 2007 conf/lfcs/2007 LFCS http://dx.doi.org/10.1007/978-3-540-72734-7_16 db/conf/lfcs/lfcs2007.html#GentiliniSM07