Kilpi, M. and Saurola, P. (1983) “Wintering areas of Great Black-backed and Herring Gulls from Heinäsaaret, the arctic USSR, and the northern Baltic in 1930–40”, Ornis Fennica, 60(3), pp. 91–93. Available at: https://ornisfennica.journal.fi/article/view/133135 (Accessed: 23November2024).