Pistrorius, Pierre A, Arne Follestad, and Frances E Taylor. “Temporal Changes in Spring Migration Phenology in the Norwegian Greylag Goose Anser Anser, 1971-2004”. Wildfowl 56 (April 16, 2013): 23–36. Accessed April 15, 2026. https://tidsskrift.dk/Wildfowl/article/view/153973.