@inproceedings{VDME-1991-Jonkers,
	author        = "H. B. M. Jonkers",
	booktitle     = "{Proceedings of the Fourth International Symposium on Vienna Development Method: Formal Software Development. Volume 1: Conference Contributions}",
	doi           = "10.1007/3-540-54834-3_26",
	isbn          = "3-540-54834-3",
	pages         = "428--456",
	publisher     = "{Springer-Verlag}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{Upgrading the Pre- and Postcondition Technique}",
	volume        = 551,
	year          = 1991,
}