Belaid Benhamou Lakhdar Sais Pierre Siegel Two Proof Procedures for a Cardinality Based Language in Propositional Calculus. 71-82 1994 conf/stacs/1994 STACS db/conf/stacs/stacs94.html#BenhamouSS94 http://dx.doi.org/10.1007/3-540-57785-8_132