HORTLING, I. Die Krähe (Corvus c. cornix L) als Zugvogel in Finnland. Ornis Fennica, [S. l.], v. 1, n. 2–3, p. 25–31, 1924. Disponível em: https://ornisfennica.journal.fi/article/view/132113. Acesso em: 11 may. 2024.