@inproceedings{SIGMOD-1977-DaleD,
	author        = "Alfred G. Dale and Nell B. Dale",
	booktitle     = "{Proceedings of the Seventh ACM SIGMOD International Conference on Management of Data}",
	cdrom         = "SIGMOD77/P102.PDF",
	doi           = "10.1145/509404.509419",
	pages         = "102--110",
	publisher     = "{ACM}",
	title         = "{Main Schema-External Schema Interaction in Hierarchically Organized Data Bases}",
	year          = 1977,
}