@inproceedings{SIGIR-2007-DowneyDH,
	author        = "Doug Downey and Susan T. Dumais and Eric Horvitz",
	booktitle     = "{Proceedings of the 30th International ACM SIGIR Conference on Research and Development in Information Retrieval}",
	doi           = "10.1145/1277741.1277939",
	isbn          = "978-1-59593-597-7",
	pages         = "847--848",
	publisher     = "{ACM}",
	title         = "{Heads and tails: studies of web search with common and rare queries}",
	year          = 2007,
}