Meire, Patrick M, Eckhart Kuijken, and Koen Devos. 1988. “Numbers and Distribution of White-Fronted and Pink-Footed Geese in Flanders (Belgium), 1981-87 in a North West European Context”. Wildfowl, January, 71-81. https://tidsskrift.dk/Wildfowl/article/view/154737.