NILSSON, L. Changes in numbers and habitat utilization of wintering Whooper Swans Cygnus cygnus in Sweden 1964—1977. Ornis Svecica, Lund, Sweden, v. 7, n. 3–4, p. 133–142, 1997. DOI: 10.34080/os.v7.22966. Disponível em: https://journals.lub.lu.se/os/article/view/22966. Acesso em: 5 dec. 2022.