@inproceedings{PODS-1982-Zaniolo,
	author        = "Carlo Zaniolo",
	booktitle     = "{Proceedings of the First Symposium on Principles of Database Systems}",
	cdrom         = "['journals/anthology/cd1-3:PODS82/P027.PDF', 'journals/anthology/dvd1:text/1-3/PODS82/P027.PDF']",
	doi           = "10.1145/588111.588117",
	isbn          = "0-89791-070-2",
	pages         = "27--33",
	publisher     = "{ACM}",
	title         = "{Database Relations with Null Values}",
	year          = 1982,
}