Bregnballe, Thomas, Ole Amstrup, Thomas E. Holm, Preben Clausen, och Anthony D. Fox. 2014. ”Skjern River Valley, Northern Europe’s Most Expensive Wetland Restoration Project: Benefits to Breeding Waterbirds”. Ornis Fennica 91 (4):231–243. https://doi.org/10.51812/of.133860.