@inproceedings{CSL-2002-BerwangerGL,
	author        = "Dietmar Berwanger and Erich Grädel and Giacomo Lenzi",
	booktitle     = "{Proceedings of the 11th EACSL Annual Conference / 16th International Workshop on Computer Science Logic}",
	doi           = "10.1007/3-540-45793-3_24",
	isbn          = "3-540-44240-5",
	pages         = "352--366",
	publisher     = "{Springer International Publishing}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{On the Variable Hierarchy of the Modal μ-Calculus}",
	volume        = 2471,
	year          = 2002,
}