Patterson, I J, and J-F Giroux. 1990. “Breeding Success of Icelandic Pink-Footed Geese Anser Brachyrhynchus and Greylag Geese A. Answer in Different Areas of Iceland in 1987 and 1988”. Wildfowl, January, 13-17. https://tidsskrift.dk/Wildfowl/article/view/154057.