1. Ullman, J. Principles of Database Systems, Second Edition. Computer Science Press, Rockville, Maryland.
2. Korth, H. and Silberschatz, A. Database System Concepts. McGraw Hill, New York, 1991.
3. Codd, E. A Relational Model for Large Shared Data Banks. Communications of the ACM, 13:6, pp. 377–387.
4. Stonebraker, M. and Rowe, L. The Design of POSTGRES. Proceedings of the International Conference of the ACM SIGMOD, Washington, D. C., May 1986.
5. Kim, W., Garza, J., and Ballou, N. and Woelk, D. Architecture of the ORION Next-Generation Database System. IEEE Transactions on Knowledge and Data Engineering, Vol. 2, No. 1, March 1990, pp. 109–124.