van Dijk, Klaas, and Mennobart R van Eerden. 2013. “Biometrics and Timing of Primary Moult of Non-Breeding Mute Swans Cygnus Olor at Lake IJsselmeer, the Netherlands”. Wildfowl, April, 296-303. https://tidsskrift.dk/Wildfowl/article/view/154961.