Christel Baier Nathalie Bertrand Patricia Bouyer Thomas Brihaye When Are Timed Automata Determinizable? 43-54 2009 ICALP (2) http://dx.doi.org/10.1007/978-3-642-02930-1_4 conf/icalp/2009-2 db/conf/icalp/icalp2009-2.html#BaierBBB09