Data Models in Database Management.

http://doi.acm.org/10.1145/800227.806891 db/conf/sigmod/Codd80.html E. F. Codd Data Models in Database Management. 112-114 PINGREE1980/P112.pdf 1980 conf/sigmod/80p Workshop on Data Abstraction, Databases and Conceptual Modelling db/conf/sigmod/pingree80.html#Codd80