PERRINS, C M; MCCLEERY, R H. Pairing behaviour in a colony of Mute Swans Cygnus olor. Wildfowl, [S. l.], p. 31–41, 1996. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/154648. Acesso em: 16 dec. 2025.