Bellebaum, J., Kube, J., Schulz, A., Skov, H. and Wendeln, H. (2014) “Decline of Long-tailed Duck Clangula hyemalis numbers in the Pomeranian Bay revealed by two different survey methods”, Ornis Fennica, 91(3), pp. 129–137. doi: 10.51812/of.133850.