@inproceedings{CAAP-1991-Luo,
	author        = "Zhaohui Luo",
	booktitle     = "{Proceedings of the Fourth International Joint Conference on Theory and Practice of Software Development, Volume 1: Colloquium on Trees in Algebra and Programming}",
	doi           = "10.1007/3-540-53982-4_9",
	isbn          = "3-540-53982-4",
	pages         = "143--168",
	publisher     = "{Springer}",
	title         = "{Program Specification and Data Refinement in Type Theory}",
	year          = 1991,
}