@inproceedings{FM-v2-1999-HehnerG,
	author        = "Eric C. R. Hehner and Andrew M. Gravell",
	booktitle     = "{Proceedings of the World Congress on Formal Methods in the Development of Computing Systems. Volume II}",
	doi           = "10.1007/3-540-48118-4_29",
	isbn          = "3-540-66588-9",
	pages         = "1497--1510",
	publisher     = "{Springer-Verlag}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{Refinement Semantics and Loop Rules}",
	volume        = 1709,
	year          = 1999,
}