@inproceedings{SAC-1993-ClementiniF,
	author        = "Eliseo Clementini and Paolino Di Felice",
	booktitle     = "{Proceedings of the Eighth Symposium on Applied Computing: States of the Art and Practice}",
	doi           = "10.1145/162754.162905",
	pages         = "302--308",
	publisher     = "{ACM Press}",
	title         = "{An Object Calculus for Geographic Databases}",
	year          = 1993,
}