@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",
  month = "July",
  pages = "57–83",
  url = "http://dx.doi.org/10.1016/j.websem.2012.03.001",
  volume = "14",
}