MCKELVEY, R W; DAVIES, R G; MORRISSON, K. The status of Trumpeter Swans Cygnus buccinator wintering on Vancouver Island, British Columbia, Canada, in 1989. Wildfowl, [S. l.], p. 84–87, 2013. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/154996. Acesso em: 17 dec. 2025.