HANSKI, I. K.; TIAINEN, J. Morphological variation in sympatric and allopatric populations of European Willow Warblers and Chiffchaffs. Ornis Fennica, [S. l.], v. 68, n. 1, p. 1–16, 1991. Disponível em: https://ornisfennica.journal.fi/article/view/133310. Acesso em: 16 may. 2024.