Daniel Johannsen Igor Razgon Magnus Wahlström Solving SAT for CNF Formulas with a One-Sided Restriction on Variable Occurrences. 80-85 2009 SAT http://dx.doi.org/10.1007/978-3-642-02777-2_10 conf/sat/2009 db/conf/sat/sat2009.html#JohannsenRW09