Nadia Creignou Henning Schnoor Ilka Schnoor Non-uniform Boolean Constraint Satisfaction Problems with Cardinality Constraint. 109-123 2008 CSL http://dx.doi.org/10.1007/978-3-540-87531-4_10 conf/csl/2008 db/conf/csl/csl2008.html#CreignouSS08