@inproceedings{STOC-1991-BeigelRS,
	author        = "Richard Beigel and Nick Reingold and Daniel A. Spielman",
	booktitle     = "{Proceedings of the 23rd Annual ACM Symposium on Theory of Computing}",
	doi           = "10.1145/103418.103426",
	isbn          = "0-89791-397-3",
	pages         = "1--9",
	publisher     = "{ACM}",
	title         = "{PP Is Closed Under Intersection}",
	year          = 1991,
}