@inproceedings{PODS-2009-CaliGL,
	author        = "Andrea Calì and Georg Gottlob and Thomas Lukasiewicz",
	booktitle     = "{Proceedings of the 28th Symposium on Principles of Database Systems}",
	doi           = "10.1145/1559795.1559809",
	isbn          = "978-1-60558-553-6",
	pages         = "77--86",
	publisher     = "{ACM}",
	title         = "{A general datalog-based framework for tractable query answering over ontologies}",
	year          = 2009,
}