Hall, C., Glanville, J., Boland, H., Einarsson, Ólafur, McElwaine, G., Holt, C. A., … Rees, E. C. (2012). Population size and breeding success of Icelandic Whooper Swans Cygnus cygnus: results of the 2010 international census. Wildfowl, 73–96. Retrieved from https://tidsskrift.dk/Wildfowl/article/view/153572