@article{WittenBell91,
	title = { The zero-frequency problem: Estimating the probabilities of novel events in adaptive text compression},
	author = {I.H. Witten and T.C. Bell},
	journal = {IEEE Transactions on Information Theory},
	number = {4},
	volume = {37},
	year = {1991},
	biburl = {http://www.bibsonomy.org/bibtex/212e2092c919f5baf57d86569584892ec/pierpaolo.pk81},
	description = {WSD},
	keywords = {imported }
}