CZAPULAK, Andrzej. Status of the Mute Swan, Cygnus olor and the Whooper Swan C. cygnus in Silesia (SW Poland). Wildfowl, [S. l.], p. 39–43, 2013. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/155009. Acesso em: 17 dec. 2025.