@inproceedings{PODS-1994-CalvaneseL,
	author        = "Diego Calvanese and Maurizio Lenzerini",
	booktitle     = "{Proceedings of the 13th Symposium on Principles of Database Systems}",
	doi           = "10.1145/182591.182620",
	isbn          = "0-89791-642-5",
	pages         = "243--254",
	publisher     = "{ACM Press}",
	title         = "{Making Object-Oriented Schemas More Expressive}",
	year          = 1994,
}