Hans van Maaren Linda van Norden Hidden Threshold Phenomena for Fixed-Density SAT-formulae. 135-149 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2919&spage=135 2003 conf/sat/2003 SAT db/conf/sat/sat2003.html#MaarenN03