1. Abiteboul, S., Hull, R., Vianu, V.: Foundations of Databases. Addison-Wesley, Reading (1995)
2. Apt, K., Bol, R.: Logic Programming and Negation: A Survey. Journal of Logic Programming 19&20, 9–71 (1994)
3. Benedikt, M., Libkin, L.: Safe constraint queries. In: PODS 1998: Proceedings of the Seventeenth ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, pp. 99–108. ACM Press, New York (1998)
4. Lecture Notes in Computer Science;S.B.P.A. Bonatti,2005
5. Bonner, A.J., McCarty, L.T., Vadaparty, K.: Expressing Database Queries with Intuitionistic Logic. In: Lusk, E.L., Overbeek, R.A. (eds.) Proceedings of the North American Conference on Logic Programming, pp. 831–850 (1989)