W. Faber, N. Leone, F. Ricca:
"Solving Hard Problems for the Second Level of the Polynomial Hierarchy: Heuristics and Benchmarks";
Report for TU Wien, Institut fuer Informationssysteme, INFSYS RR-1843-05-09; 2005; 14 pages.
http://publik.tuwien.ac.at/files/pub-inf_3534.pdf