@inproceedings{DLT-2008-KlimaP,
	author        = "Ondrej Klíma and Libor Polák",
	booktitle     = "{Proceedings of the 12th International Conference on Developments in Language Theory}",
	doi           = "10.1007/978-3-540-85780-8_38",
	isbn          = "978-3-540-85779-2",
	pages         = "479--490",
	publisher     = "{Springer International Publishing}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{Hierarchies of Piecewise Testable Languages}",
	volume        = 5257,
	year          = 2008,
}