1. Fundamentals of Database Systems (2ndEdition);Elmasri,1994
2. H. Mannila, K. J. Raiha, Proceedings of 8thACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, 128, 133
3. C. J. Date, An Introduction to Database Systems (6thEdition), 309, 317
4. T. Connolly, C. Begg, Database Systems, A Practical Approach to Design, Implementation and Management (2ndEdition), 193