@inproceedings{DBLP:conf/sebd/CaliGP10,
  title = "Tractable Query Answering over Conceptual Schemata (Extended Abstract)",
  author = "Andrea Cal\`{\i} and Georg Gottlob and Andreas Pieris",
  year = "2010",
  booktitle = "Proceedings of the 18th Italian Symposium on Advanced Database Systems (SEBD)",
}