@inproceedings{STOC-1971-Buttelmann,
	author        = "H. W. Buttelmann",
	booktitle     = "{Proceedings of the Third Annual ACM Symposium on Theory of Computing}",
	doi           = "10.1145/800157.805039",
	pages         = "63--77",
	publisher     = "{ACM}",
	title         = "{On Generalized Finite Automata and Unrestricted Generative Grammars}",
	year          = 1971,
}