. Abiteboul, Terminological cycles in a description logic with existential restrictions, MichelLecì ere, Marie-Laure Mugnier, and Eric Salvat. On Rules with Existential Variables: Walking the Decidability Line, vol.175, pp.1620-1654, 1994.

C. , Mélanie König, MichelLecì ere, MarieLaure Mugnier, and Michaël Thomazo. A sound and complete backward chaining algorithm for existential rules, General Datalog-Based Framework for Tractable Query Answering over Ontologies. In PODS, vol.39, pp.489-504, 2005.