E.F. Codd: "Notes on a Data Sublanguage." IBM internal memo (January 19, 1970).
E.F. Codd: "A Data Base Sublanguage Founded on the Relational Calculus." IBM Research report RJ893 (July 26, 1971). Republished in Proc. 1971 ACM SIGFIDET Workshop on Data Description, Access and Control, San Diego, Calif. (November 1971).
E.F. Codd: Private communication (March 14, 1972).
E.F. Codd and C.J. Date: "Interactive Support for Nonprogrammers: The Relational and Network Approaches." IBM Research Report RJ1400 (June 6, 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). See also E.F. Codd: "The Significance of the SQL / Data System Announcement." IBM Report (January 30, 1981).
Hugh Darwen and C.J. Date: "The Third Manifesto." ACM SIGMOD Record 24, No. 1 (March 1995). Version Two of this document is in preparation in the time of writing.
C.J. Date: "An Introduction to the Unified Database Language (UDL)." Proc. 6th International Conference on Very Large Data Bases, Montreal, Canada (September/October 1980). Republished (in considerably revised form) in C.J. Date, Relational Database: Selected Writings, Addison-Wesley (1986).
C.J. Date: "A Critique of the SQL Database Language." ACM SIGMOD Record 14, No. 3 (November 1984). Republished in C.J. Date, Relational Database: Selected Writings. Reading, Mass.: Addison-Wesley (1986).
C.J. Date: A Guide to Ingres. Reading, Mass.: Addison-Wesley (1987).
