@inproceedings{PLDI-1991-FreemanP,
	author        = "Tim Freeman and Frank Pfenning",
	booktitle     = "{Proceedings of the 12th Conference on Programming Language Design and Implementation}",
	doi           = "10.1145/113445.113468",
	editor        = "David S. Wise",
	isbn          = "0-89791-428-7",
	pages         = "268--277",
	publisher     = "{ACM}",
	title         = "{Refinement Types for ML}",
	year          = 1991,
}