THOMAS, G J; OWEN, Myrfyn; RICHARDS, Penny. Grit in waterfowl at the Ouse Washes, England. Wildfowl, [S. l.], p. 3, 1977. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/154354. Acesso em: 13 feb. 2026.