Scott Aaronson Salman Beigi Andrew Drucker Bill Fefferman Peter W. Shor The Power of Unentanglement. 223-236 2008 IEEE Conference on Computational Complexity http://doi.ieeecomputersociety.org/10.1109/CCC.2008.5 conf/coco/2008 db/conf/coco/coco2008.html#AaronsonBDFS08