@inproceedings{ijcai2003p3,
  title     = {Query rewriting and answering under constraints in data integration systems},
  author    = {Calì, Andrea and Lembo, Domenico and Rosati, Riccardo},
  booktitle = {Proceedings of the Eighteenth International Joint Conference on
               Artificial Intelligence, {IJCAI-03}},
  publisher = {International Joint Conferences on Artificial Intelligence},
  editor    = {Georg Gottlob},
  pages     = {16--20},
  year      = {2003},
  url       = {https://ijcai.org/proceedings/2003/3},
}