@inproceedings{ICALP-1990-Kuich,
	author        = "Werner Kuich",
	booktitle     = "{Proceedings of the 17th International Colloquium on Automata, Languages and Programming}",
	doi           = "10.1007/BFb0032025",
	isbn          = "3-540-52826-1",
	pages         = "103--110",
	publisher     = "{Springer-Verlag}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{ω-Continuous Semirings, Algebraic Systems and Pushdown Automata}",
	volume        = 443,
	year          = 1990,
}