@inproceedings{EDM-2009-StamperB,
	author        = "John C. Stamper and Tiffany Barnes",
	booktitle     = "{Educational Data Mining — EDM 2009, Cordoba, Spain, July 1-3, 2009. Proceedings of the Second International Conference on Educational Data Mining}",
	ee            = "http://www.educationaldatamining.org/EDM2009/uploads/proceedings/stamper.pdf",
	isbn          = "978-84-613-2308-1",
	pages         = "181--190",
	publisher     = "{www.educationaldatamining.org}",
	title         = "{An unsupervised, frequency-based metric for selecting hints in an MDP-based tutor}",
	year          = 2009,
}