@inproceedings{STOC-1969-Ullian,
	author        = "Joseph S. Ullian",
	booktitle     = "{Proceedings of the First Annual ACM Symposium on Theory of Computing}",
	doi           = "10.1145/800169.805417",
	pages         = "19--20",
	publisher     = "{ACM}",
	title         = "{The Inherent Ambiguity Partial Algorithm Problem for Context Free Languages}",
	year          = 1969,
}