Bergman, G. (1980) “Single-breeding versus colonial breeding in the Caspian Tern Hydroprogne caspia, the Common Tern Sterna hirundo and the Arctic Tern Sterna paradisaea”, Ornis Fennica, 57(4), pp. 141–152. Available at: https://ornisfennica.journal.fi/article/view/133049 (Accessed: 23November2024).