E. F. Codd. Understanding Relations. SIGMOD Record, 5(1):63-64, 1973. [doi]
@article{Codd73,
title = {Understanding Relations},
author = {E. F. Codd},
year = {1973},
doi = {10.1145/983055.983059},
url = {http://doi.acm.org/10.1145/983055.983059},
tags = {e-science},
researchr = {https://researchr.org/publication/Codd73},
cites = {0},
citedby = {0},
journal = {SIGMOD Record},
volume = {5},
number = {1},
pages = {63-64},
}