@inproceedings{SIGMOD-1978-HammerM,
	author        = "Michael Hammer and Dennis McLeod",
	booktitle     = "{Proceedings of the Eighth ACM SIGMOD International Conference on Management of Data}",
	cdrom         = "SIGMOD78/P026.PDF",
	doi           = "10.1145/509252.509264",
	pages         = "26--36",
	publisher     = "{ACM}",
	title         = "{The Semantic Data Model: A Modelling Mechanism for Data Base Applications}",
	year          = 1978,
}