OGILVIE, M A; BOYD, H. The numbers of Pink-footed and Greylag Geese wintering in Britain: observations 1969-1975 and predictions 1976-1980. Wildfowl, [S. l.], p. 63–76, 1976. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/154327. Acesso em: 18 dec. 2025.