Edgar F. Codd:A Relational Model of Data for Large Shared Data Banks. In: Communications of the ACM. ACM Press, 13.Juni 1970, ISSN0001-0782, S.377–387 (englisch, acm.org).
Edgar F. Codd:A Relational Model of Data for Large Shared Data Banks. In: Communications of the ACM. ACM Press, 13.Juni 1970, ISSN0001-0782, S.377–387 (englisch, acm.org).