McKelvey, R W, R G Davies, and K Morrisson. “The Status of Trumpeter Swans Cygnus Buccinator Wintering on Vancouver Island, British Columbia, Canada, in 1989”. Wildfowl (April 16, 2013): 84–87. Accessed December 17, 2025. https://tidsskrift.dk/Wildfowl/article/view/154996.