@inproceedings{FME-1993-Ward,
	author        = "Nigel Ward",
	booktitle     = "{Proceedings of the First International Symposium of Formal Methods Europe: Industrial-Strength Formal Methods}",
	doi           = "10.1007/BFb0024672",
	isbn          = "3-540-56662-7",
	pages         = "652--670",
	publisher     = "{Springer-Verlag}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{Adding Specification Constructors to the Refinement Calculus}",
	volume        = 670,
	year          = 1993,
}