@inproceedings{STOC-1974-Greibach,
	author        = "Sheila A. Greibach",
	booktitle     = "{Proceedings of the Sixth Annual ACM Symposium on Theory of Computing}",
	doi           = "10.1145/800119.803903",
	pages         = "256--265",
	publisher     = "{ACM}",
	title         = "{Some Restrictions on W-Grammars}",
	year          = 1974,
}