Ullman, J. D. (1982). Principles of Database Systems (2nd ed.). Computer Science Press.
Cita Chicago (17th ed.)Ullman, Jeffrey D. Principles of Database Systems. 2nd ed. 11 Taft Court, Rockville, Maryland 20850: Computer Science Press, 1982.
Cita MLA (9th ed.)Ullman, Jeffrey D. Principles of Database Systems. 2nd ed. Computer Science Press, 1982.
Atenció: Aquestes cites poden no estar 100% correctes.