Lars Grunske Kirsten Winter Robert Colvin Timed Behavior Trees and Their Application to Verifying Real-Time Systems. 211-222 2007 ASWEC http://doi.ieeecomputersociety.org/10.1109/ASWEC.2007.49 conf/aswec/2007 db/conf/aswec/aswec2007.html#GrunskeWC07