Kilpi, M., and P. Saurola. “Wintering Areas of Great Black-Backed and Herring Gulls from Heinäsaaret, the Arctic USSR, and the Northern Baltic in 1930–40”. Ornis Fennica 60, no. 3 (September 30, 1983): 91–93. Accessed November 23, 2024. https://ornisfennica.journal.fi/article/view/133135.