Mary Sheeran Gunnar Stålmarck A Tutorial on Stålmarcks's Proof Procedure for Propositional Logic. 82-99 http://link.springer.de/link/service/series/0558/bibs/1522/15220082.htm 1998 conf/fmcad/1998 FMCAD db/conf/fmcad/fmcad1998.html#SheeranS98