@inproceedings{ICALP-1986-Straubing,
	author        = "Howard Straubing",
	booktitle     = "{Proceedings of the 13th International Colloquium on Automata, Languages and Programming}",
	doi           = "10.1007/3-540-16761-7_91",
	isbn          = "3-540-16761-7",
	pages         = "416--423",
	publisher     = "{Springer-Verlag}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{Semigroups and Languages of Dot-Depth 2}",
	volume        = 226,
	year          = 1986,
}