Jean-Francois (2002).  A Comparison of Control Problems for Timed and Hybrid Systems . Retrieved 2010-03-02 . ^   Borges, Jorge Luis  (1964).  Labyrinths . London:  Penguin . pp. 237–243.  ISBN   0811200124 . References Kirk, G. S. ,  J. E. Raven , M. Schofield (1984)  The Presocratic Philosophers: A Critical History with