http://doi.acm.org/10.1145/800227.806873 db/conf/sigmod/Rowe80.html Lawrence A. Rowe Data Abstraction From a Programming Language Viewpoint. 29-35 PINGREE1980/P029.pdf 1980 conf/sigmod/80p Workshop on Data Abstraction, Databases and Conceptual Modelling db/conf/sigmod/pingree80.html#Rowe80