PERRINS, C M; REYNOLDS, C M. A preliminary study of the Mute Swan, Cygnus olor. Wildfowl, [S. l.], v. 18, p. 74–84, 1967. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/155610. Acesso em: 5 apr. 2026.