Jacobsen, B. V., & Sonerud, G. A. (1993). Synchronous switch in diet and hunting habitats as a response to disappearance of snow cover in Tengmalm´s Owl Aegolius funereus. Ornis Fennica, 70(2), 78–88. Hämtad från https://ornisfennica.journal.fi/article/view/133367