@inproceedings{SIGMOD-1985-Ullman,
	author        = "Jeffrey D. Ullman",
	booktitle     = "{Proceedings of the 15th ACM SIGMOD International Conference on Management of Data}",
	cdrom         = "SIGMOD85/P444.PDF",
	doi           = "10.1145/318898.320000",
	pages         = "444",
	publisher     = "{ACM Press}",
	title         = "{Implementation of Logical Query Languages for Databases}",
	year          = 1985,
}