@inbook {Hession2006Accuracy,
	title = {{Categorical models for spatial data uncertainty}},
	booktitle = {Proceedings of the 7th International Symposium on Spatial Accuracy Assessment in Natural Resources and Environmental Sciences (Accuracy 2006)},
	year = {2006},
	pages = {386-395},
	publisher = {Instituto Geogr{\'a}phico Portugu{\^e}s},
	organization = {Instituto Geogr{\'a}phico Portugu{\^e}s},
	address = {Lisbon},
	author = {Hession, S.~L. and Shortridge, A.~M. and Torbick, M.~N.},
	editor = {Caetano, M. and Painho, M.}
}