Ferdinand Börner Andrei A. Bulatov Peter Jeavons Andrei A. Krokhin Quantified Constraints: Algorithms and Complexity. 58-70 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2803&spage=58 2003 conf/csl/2003 CSL db/conf/csl/csl2003.html#BornerBJK03