SIIVONEN, L. Does the Willow Warbler, Phylloscopus trochilus (L.), belong to those species of birds fluctuating greatly in number. Ornis Fennica, [S. l.], v. 26, n. 4, p. 89–97, 1949. Disponível em: https://ornisfennica.journal.fi/article/view/132521. Acesso em: 18 may. 2024.