Nilsson, Leif, and Hakon Persson. “Field Choice of Staging Greylag Geese Anser Anser in Relation to Changes in Agriculture in South Sweden”. Ornis Svecica 8, no. 1–2 (April 1, 1998): 27–39. Accessed July 7, 2022. https://journals.lub.lu.se/os/article/view/22958.