E.F. Codd and C.J. Date. "Interactive Support for Nonprogrammers: The Relational and Network Approaches." IBM Research Report RJ1400 (June 6th, 1974). Republished in Randall J. Rustin (ed.), Proc. ACM SIGMOD Workshop on Data Description, Access, and Control, Vol. II, Ann Arbor, Michigan (May 1974). Also in C.J. Date, Relational Database: Selected Writings, Reading, Mass.: Addison-Wesley (1986).
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Date, C.J. "Support for the Conceptual Schema: The Relational and Network Approaches." In C.J. Date, Relational Database Writings 1985-1989. Reading, Mass.: Addison-Wesley (1990).
Codd, E.F. "Normalized Data Base Structure: A Brief Tutorial." Proc. 1971 ACM SIGFIDET Workshop on Data Description, Access, and Control, San Diego, Calif. (November 11th-12th, 1971).
