SITS, E. Die Invasion der Schnee-Eule in Eesti (Estland) im Winter 1935–36. Ornis Fennica, [S. l.], v. 14, n. 1, p. 36–37, 1937. Disponível em: https://ornisfennica.journal.fi/article/view/132359. Acesso em: 20 may. 2024.