System R: A Relational Data Base Management System
Astrahan, Blasgen, Chamberlin, Gray, King, Lindsay, Lorie, Mehl, Price, Putzolu, Schkolnick, Selinger, Slutz, strong, Tiberio, Traiger, Wade, Yost · Computer · 1979
A relational approach makes this experimental data base management system unusually easy to install and use. Some of the decisions made in System R design in order to enhance usability also offer major bonuses in other areas.