Enrico Giunchiglia Roberto Sebastiani Applying the Davis-Putnam Procedure to Non-clausal Formulas. 84-94 http://link.springer.de/link/service/series/0558/bibs/1792/17920084.htm 1999 conf/aiia/1999 AI*IA db/conf/aiia/aiia1999.html#GiunchigliaS99