@article{DBLP:journals/jws/CGL11,
  title = "A general Datalog-based framework for tractable query answering over ontologies",
  author = "Andrea Cal\`{i} and Georg Gottlob and Thomas Lukasiewicz",
  year = "2012",
  journal = "Journal of Web Semantics",
  note = "In press.",
  url = "http://dx.doi.org/10.1016/j.websem.2012.03.001",
}