@inproceedings{VLDB-1981-Goldstein,
	author        = "Billie S. Goldstein",
	booktitle     = "{Proceedings of the Seventh International Conference on Very Large Data Bases}",
	cdrom         = "VLDB81/P101.PDF",
	pages         = "101--110",
	publisher     = "{IEEE Computer Society}",
	title         = "{Constraints on Null Values in Relational Databases}",
	year          = 1981,
}