BOIKO, Dmitrijs; KAMPE-PERSSON, Hakon. Winter distribution of Whooper Swans Cygnus cygnus cygnets bred in Latvia, 2004-2008. Wildfowl, [S. l.], p. 74–89, 2013. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/153549. Acesso em: 13 feb. 2026.