@inproceedings{SIGMOD-1981-Sato,
	author        = "H. Sato",
	booktitle     = "{Proceedings of the 11th ACM SIGMOD International Conference on Management of Data}",
	cdrom         = "SIGMOD81/P098.PDF",
	doi           = "10.1145/582318.582334",
	pages         = "98--107",
	publisher     = "{ACM Press}",
	title         = "{Handling Summary Information in a Database: Derivability}",
	year          = 1981,
}