Hario, M., and J. Rintala. “Age of First Breeding in the Common Eider Somateria M. Mollissima Population in the Northern Baltic Sea”. Ornis Fennica 86, no. 3 (September 30, 2009): 81–88. Accessed May 13, 2024. https://ornisfennica.journal.fi/article/view/133724.