http://doi.acm.org/10.1145/800296.811518 db/conf/sigmod/SteuertG74.html James Steuert Jay Goldman The Relational Data Management System: A Perspective. 295-320 SIGFIDET74-1/P295.pdf 1974 conf/sigmod/74 SIGMOD Workshop, Vol. 1 db/conf/sigmod/sigmod74-1.html#SteuertG74