Franson, J. C., T. Hollmén, M, M. Hario, M. Kilpi, and D. L. Finley. 2002. “Lead and Delta-Aminolevulinic Acid Dehydratase in Blood of Common Eiders (Somateria Mollissima) from the Finnish Archipelago”. Ornis Fennica 79 (2):87–91. https://ornisfennica.journal.fi/article/view/133575.