@inproceedings{SIGMOD-1989-Jagadish,
	author        = "H. V. Jagadish",
	booktitle     = "{Proceedings of the 19th ACM SIGMOD International Conference on Management of Data}",
	cdrom         = "SIGMOD89/P078.PDF",
	doi           = "10.1145/67544.66934",
	pages         = "78--87",
	title         = "{Incorporating Hierarchy in a Relational Model of Data}",
	year          = 1989,
}