@inproceedings{POPL-1973-WaldingerL,
	author        = "Richard J. Waldinger and Karl N. Levitt",
	booktitle     = "{Conference Record of the First Symposium on Principles of Programming Languages}",
	doi           = "10.1145/512927.512943",
	editor        = "Patrick C. Fischer and Jeffrey D. Ullman",
	pages         = "169--182",
	publisher     = "{ACM Press}",
	title         = "{Reasoning About Programs}",
	year          = 1973,
}