Marcello Balduccini Michael Gelfond Richard Watson Monica Nogueira The USA-Advisor: A Case Study in Answer Set Planning. 439-442 2001 conf/lpnmr/2001 LPNMR http://link.springer.de/link/service/series/0558/bibs/2173/21730439.htm db/conf/lpnmr/lpnmr2001.html#BalducciniGWN01