M. Lemmon, T. Chantem, X. Hu, and M. Zyskowski. Proceedings of the 10th international conference on Hybrid systems: computation and control, page 371--384. Berlin, Heidelberg, Springer-Verlag, (2007)
A. Anta, and P. Tabuada. Decision and Control, 2009 held jointly with the 2009 28th Chinese Control Conference. CDC/CCC 2009. Proceedings of the 48th IEEE Conference on, page 3194 -3199. (December 2009)