Thao Dang Alexandre Donzé Oded Maler Verification of Analog and Mixed-Signal Circuits Using Hybrid System Techniques. 21-36 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3312&spage=21 2004 conf/fmcad/2004 FMCAD db/conf/fmcad/fmcad2004.html#DangDM04