@inproceedings{VLDB-1981-ImielinskiL,
	author        = "Tomasz Imielinski and Witold Lipski Jr.",
	booktitle     = "{Proceedings of the Seventh International Conference on Very Large Data Bases}",
	cdrom         = "VLDB81/P388.PDF",
	pages         = "388--397",
	publisher     = "{IEEE Computer Society}",
	title         = "{On Representing Incomplete Information in a Relational Data Base}",
	year          = 1981,
}