@inproceedings{STOC-1971-Machtey,
	author        = "Michael Machtey",
	booktitle     = "{Proceedings of the Third Annual ACM Symposium on Theory of Computing}",
	doi           = "10.1145/800157.805054",
	pages         = "251--257",
	publisher     = "{ACM}",
	title         = "{Classification of Computable Functions by Primitive Recursive Classes}",
	year          = 1971,
}