CHOVAN, Alexander A.; KAZANNIK, Vitaly V. The present status of Bewick’s Swans Cygnus columbianus bewickii in Ukraine. Wildfowl, [S. l.], v. 65, p. 143–153, 2015. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/153667. Acesso em: 15 apr. 2026.