Hermann Kopetz Christian El Salloum Bernhard Huber Roman Obermaisser Periodic Finite-State Machines. 10-20 2007 ISORC http://doi.ieeecomputersociety.org/10.1109/ISORC.2007.47 conf/isorc/2007 db/conf/isorc/isorc2007.html#KopetzSHO07