@TechReport{ddd-timedsystems-99,
  author = 	 {J. M{\o}ller and J. Lichtenberg and 
                  H. R. Andersen and H. Hulgaard},
  title = 	 {On the Symbolic Verification of Timed Systems},
  institution =  {Department of Information Technology, 
                  Technical University of Denmark},
  year = 	 1999,
  number = 	 {IT-TR-1999-024},
  address =      {Building 344, DK-2800 Lyngby, Denmark},
  month =        feb
}