BOWLER, Jonathan M; BUTLER, Linda; LIGGETT, Charlie; REES, Eileen C. Bewick’s and Whooper Swans Cygnus columbianus bewickii and C. cygnus: the 1993-94 season. Wildfowl, [S. l.], p. 269–275, 2025. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/155862. Acesso em: 16 dec. 2025.