1. [Baget and Mugnier, 2002] Baget, J.-F., Mugnier, M.-L.: Extensions of simple conceptual graphs: the complexity of rules and constraints. Journal of Artificial Intelligence research (JAIR) 16, 425–465 (2002)
2. [Calvanese and Rosati, 2003] Calvanese, D., Rosati, R.: Answering recursive queries under keys and foreign keys is undecidable. In: Proc. of the 10th Int. Workshop on Knowledge Representation meets Databases (KRDB 2003), pp. 3–14 (2003), CEUR Electronic Workshop Proceedings http://ceur-ws.org/Vol-79/
3. [Calvanese et al., 2000] Calvanese, D., De Giacomo, G., Lenzerini, M.: Answering queries using views over description logics knowledge bases. In: Proc. of the 16th Nat. Conf. on Artificial Intelligence (AAAI 2000), pp. 386–391 (2000)
4. [Calvanese et al., 2004] Calvanese, D., De Giacomo, G., Lembo, D., Lenzerini, M., Rosati, R.: What to ask to a peer: ontology-based query reformulation. In: Proc. of the 9th Int. Conf. on the Principles of Knowledge Representation and Reasoning, KR 2004 (2004)
5. [Donini et al., 1998a] Donini, F.M., Lenzerini, M., Nardi, D., Nutt, W., Schaerf, A.: An epistemic operator for description logics. Artificial Intelligence 100(1-2), 225–274 (1998)