GRESS, Carol; BYERS, Jacob W; JENNINGS, Emily; ELY, Craig. Behaviour of wintering Tundra Swans Cygnus columbianus columbianus at the Eel River delta and Humboldt Bay, California, USA. Wildfowl, [S. l.], p. 38–51, 2013. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/153540. Acesso em: 16 dec. 2025.