ATKINSON-WILLES, G L; FRITH, J C. Trends in the population of British wintering ducks 1961-64. Wildfowl, [S. l.], v. 16, p. 9, 1965. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/155161. Acesso em: 5 apr. 2026.