JOHNSTONE, S T. Waterfowl collection at Slimbridge 1955-56 - The Breeding Season 1956. Wildfowl, [S. l.], v. 8, p. 35–42, 1956. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/156145. Acesso em: 19 apr. 2026.