@inproceedings{WLC-2000-Matsuda,
	author        = "Ryuki Matsuda",
	booktitle     = "{Proceedings of the Third International Colloquium on Words, Languages & Combinatorics}",
	isbn          = "978-9810249489",
	pages         = "339--351",
	publisher     = "{World Scientific}",
	title         = "{Characterization of Valuation Rings and Valuation Semigroups by Semistar-Operations}",
	year          = 2000,
}