BEEKMAN, Jan et al. Long-term population trends and shifts in distribution of Bewick’s Swans Cygnus columbianus bewickii wintering in northwest Europe. Wildfowl, [S. l.], p. 73–102, 2019. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/154488. Acesso em: 13 feb. 2026.