@inproceedings{CCPSD-1991-RamalingamR,
	author        = "G. Ramalingam and Thomas W. Reps",
	booktitle     = "{Proceedings of the Fourth International Joint Conference on Theory and Practice of Software Development, Volume 2: Colloquium on Combining Paradigms for Software Development}",
	doi           = "10.1007/3540539816_65",
	isbn          = "3-540-53981-6",
	pages         = "137--152",
	publisher     = "{Springer}",
	title         = "{A Theory of Program Modifications}",
	year          = 1991,
}