@inproceedings{LICS-1992-Hella,
	author        = "Lauri Hella",
	booktitle     = "{Proceedings of the Seventh Annual Symposium on Logic in Computer Science}",
	doi           = "10.1109/LICS.1992.185548",
	isbn          = "0-8186-2735-2",
	pages         = "360--368",
	publisher     = "{IEEE Computer Society}",
	title         = "{Logical Hierarchies in PTIME}",
	year          = 1992,
}