Codd, E.F. "Extending the Relational Database Model to Capture More Meaning." IBM Research Report RJ2599 (August 6th, 1979). Republished in ACM Transactions on Database Systems 4(4), December 1979.
Codd, E.F. "A Data Sublanguage Founded on the Relational Calculus." IBM Research Report RJ893 (July 26th, 1971). Republished in Proc. 1971 ACM SIGFIDET Workshop on Data Description, Access and Control, San Diego, November 1971.
Codd, E.F. "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.
Codd, E.F. "Recent Investigations into Relational Data Base Systems". IBM Research Report RJ1385 (April 13rd, 1974). Republished in Proc. 1974 Congress (Stockholm, 1974). New York, N.Y.: North-Holland, 1974.
Codd, E.F. "Relational Database: A Practical Foundation for Productivity." IBM Research Report RJ3339 (December 21st, 1981. Republished in CACM 25(2), February 1982.
Codd, E.F. "Data Models in Database Management. Proc. Workshop in Data Abstraction, Databases, and Conceptual Modelling (Michael L. Brodie and Stephen N. Zilles, eds.), Pingree Park, Colo. (June 1980): ACM SIGART Newsletter No. 74 (January 1981); ACM SIGMOD Record 11(2), February 1981; ACM SIGPLAN Notices 16(1), January 1981.
Stonebraker, Michael. Introduction to Chapter 1 ("The Roots"). Readings in Database Systems (2nd edition). San Mateo, Calif.: Morgan Kaufmann, 1994.
Codd, E.F. "A Relational Model of Data for Large Shared Data Banks." CACM 13(6), June 1970. Republished in Milestones of Research -- Selected Papers 1958-1982 (CACM 25th Anniversary Issue), CACM 26(1), January 1983.
Codd, E.F. "Is Your DBMS Really Relational?"; "Does Your DBMS Run By The Rules?" Computerworld (October 14th, 1985; October 21st, 1985).
Codd, E.F. The Relational Model For Database Management Version 2. Reading, Mass.: Addison-Wesley, 1990.
Date, C.J. and Hugh Darwen. Foundation for Object/Relational Databases: The Third Manifesto. Reading, Mass.: Addison-Wesley, 1998.
