MIKAMI, Shiro. First Japanese records of crosses between Whistling Cygnus columbianus columbianus and Bewick’s Swans C. c. bewickii. Wildfowl, [S. l.], p. 131–133, 1989. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/154009. Acesso em: 17 dec. 2025.