VOIPIO, P. On certain morphic characteristics of the Northern European Bullfinch (Pyrrhula pyrrhula). Ornis Fennica, [S. l.], v. 38, n. 3–4, p. 81–92, 1961. Disponível em: https://ornisfennica.journal.fi/article/view/132662. Acesso em: 19 sep. 2024.