Korpimäki, E. “Diet of Breeding Tengmalm`s Owls Aegolius Funereus: Long-Term Changes and Year-to-Year Variation under Cyclic Food Conditions”. Ornis Fennica, vol. 65, no. 1, Mar. 1988, pp. 21–30, https://ornisfennica.journal.fi/article/view/133252.