@inproceedings{SIGMOD-1990-MotroY,
	author        = "Amihai Motro and Qiuhui Yuan",
	booktitle     = "{Proceedings of the 20th ACM SIGMOD International Conference on Management of Data}",
	cdrom         = "SIGMOD90/P173.PDF",
	doi           = "10.1145/93597.98727",
	pages         = "173--183",
	title         = "{Querying Database Knowledge}",
	year          = 1990,
}