Schummer, Michael A., Allison B. Anthony, Shannon M. Kleespies, Greyson Ankenman, Michael Ligouri, Adam Bleau, Justin Droke, et al. 2020. “Aggression and Behavioural Dominance in Wintering Mallard Anas Platyrhynchos and American Black Duck A. Rubripes”. Wildfowl, November, 167-78. https://tidsskrift.dk/Wildfowl/article/view/154563.