@inproceedings{STOC-1971-Wagner,
	author        = "Eric G. Wagner",
	booktitle     = "{Proceedings of the Third Annual ACM Symposium on Theory of Computing}",
	doi           = "10.1145/800157.805034",
	pages         = "12--23",
	publisher     = "{ACM}",
	title         = "{An Algebraic Theory of Recursive Definitions and Recursive Languages}",
	year          = 1971,
}