3 literature references for Olor bewickii (Yarrell, 1830):

Year: 1996
Source: database, NODC Taxonomic Code
Author: del Hoyo, Josep, Andrew Elliott, and Jordi Sargatal, eds.
Year: 1992
Title: Ostrich to Ducks
Source: Handbook of the Birds of the World, vol. 1
Author: Stejneger, Leonhard
Year: 1882
Title: Outlines of a Monograph of the Cygninae
Source: Proceedings of the United States National Museum, vol. 5