Manfred Droste Karin Quaas A Kleene-Schützenberger Theorem for Weighted Timed Automata. 142-156 2008 FoSSaCS http://dx.doi.org/10.1007/978-3-540-78499-9_11 conf/fossacs/2008 db/conf/fossacs/fossacs2008.html#DrosteQ08