PIETZ, P J; BUHL, D A. Behaviour patterns of Mallard Anas Platyrhynchos pairs and broods in Minnesota and North Dakota. Wildfowl, [S. l.], p. 101–122, 1999. Disponível em: https://tidsskrift.dk/Wildfowl/article/view/154584. Acesso em: 17 dec. 2025.