NILSSON, Leif; ANDERSSON, Ove; GUSTAFSSON, Rolf; SVENSSON, Mikael. Increase and changes in distribution of breeding Whooper Swans Cygnus cygnus in northern Sweden from 1972-75 to 1997. Wildfowl, [S. l.], p. 6–17, 1998. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/154602. Acesso em: 17 dec. 2025.