1. Lect Notes Comput Sci;A.I. Abdelmoty,1994
2. D. Aquilino, P. Asirelli, A. Formuso, C. Renso, and F. Turini. Using MedLan to Integrate Geographical Data. Journal of Logic Programming, 43(1):3–14, 2000.
3. A. Belussi, E. Bertino, and B. Catania. An extended algebra for constraint databases. IEEE TKDE, 10(5):686–705, 1998.
4. Lect Notes Comput Sci,1999
5. K.A. Bowen and R.A. Kowalski. Amalgamating language and metalanguage in logic programming. In Logic programming, volume 16 of APIC studies in data processing, pages 153–172. Academic Press, 1982.