@article{DBLP:journals/dke/ElmasriWH85,
author = {Ramez Elmasri and
James A. Weeldreyer and
Alan R. Hevner},
title = {The Category Concept: An Extension to the Entity-Relationship
Model},
journal = {Data Knowl. Eng.},
volume = {1},
number = {1},
year = {1985},
pages = {75-116},
ee = {http://dx.doi.org/10.1016/0169-023X(85)90027-8},
bibsource = {DBLP, http://dblp.uni-trier.de}
}