Bregnballe, Thomas, Ole Amstrup, Thomas E. Holm, Preben Clausen, och Anthony D. Fox. ”Skjern River Valley, Northern Europe’s Most Expensive Wetland Restoration Project: Benefits to Breeding Waterbirds”. Ornis Fennica 91, no. 4 (december 31, 2014): 231–243. åtkomstdatum maj 17, 2024. https://ornisfennica.journal.fi/article/view/133860.