Stephan Kottler Michael Kaufmann Carsten Sinz A New Bound for an NP-Hard Subclass of 3-SAT Using Backdoors. 161-167 2008 SAT http://dx.doi.org/10.1007/978-3-540-79719-7_16 conf/sat/2008 db/conf/sat/sat2008.html#KottlerKS08a