Koivusaari, J., I. Nuuja, R. Palokangas, and V. Vihko. 1972. “Decrease in Eggshell Thickness of the Wite-Tailed Eagle in Finland During 1884–1971”. Ornis Fennica 49 (1):11–13. https://ornisfennica.journal.fi/article/view/132830.