Coba jelasin Lihat pula dari Edgar F. Codd dong

Codd, E.F. (1970), "A Relational Model of Data for Large Shared Data Banks", Eprint , Communications of the ACM, 13(6), 377–387.

National Academy of Sciences (1999), "The Rise of Relational Databases", Eprint, Chapt. 6 in Funding a Revolution: Government Support for Computing Research, Eprint, National Academy Press, Washington DC, USA, 1999.