Ulfvens, J. 1986. “Mercury Content in Eggs of the Great Crested Grebe Podiceps Cristatus and the Horned Grebe Podiceps Auritus in the Archipelago of Korsnäs, Gulf of Bothnia”. Ornis Fennica 63 (3):92–93. https://ornisfennica.journal.fi/article/view/133214.