@inproceedings{PPDP-2003-Rossberg,
	author        = "Andreas Rossberg",
	booktitle     = "{Proceedings of the Fifth International Conference on Principles and Practice of Declarative Programming}",
	doi           = "10.1145/888251.888274",
	isbn          = "1-58113-705-2",
	pages         = "241--252",
	publisher     = "{ACM}",
	title         = "{Generativity and dynamic opacity for abstract types}",
	year          = 2003,
}