@inproceedings{VLDB-1981-Warren,
	author        = "David H. D. Warren",
	booktitle     = "{Proceedings of the Seventh International Conference on Very Large Data Bases}",
	cdrom         = "VLDB81/P272.PDF",
	pages         = "272--281",
	publisher     = "{IEEE Computer Society}",
	title         = "{Efficient Processing of Interactive Relational Data Base Queries expressed in Logic}",
	year          = 1981,
}