Palmgren, P. “Der Nistbiotop Des Sperbers, Accipiter N. Nisus (L.), Auf Den Ålands-Inseln”. Ornis Fennica 9, no. 3 (September 30, 1932): 74–78. Accessed May 15, 2024. https://ornisfennica.journal.fi/article/view/132285.