NELSON, C H. Eye-colour changes in flightless ducklings of Lesser and Greater Scaup Aythya affinis and A. marila. Wildfowl, [S. l.], p. 195–198, 1996. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/154636. Acesso em: 16 dec. 2025.