@inproceedings{CIKM-2009-SunLL,
	author        = "Aixin Sun and Ee-Peng Lim and Ying Liu",
	booktitle     = "{Proceedings of the 18th ACM International Conference on Information and Knowledge Management}",
	doi           = "10.1145/1645953.1646258",
	isbn          = "978-1-60558-512-3",
	pages         = "1891--1894",
	publisher     = "{ACM}",
	title         = "{What makes categories difficult to classify?: a study on predicting classification performance for categories}",
	year          = 2009,
}