Andersson, Stina, Daniel Bengtsson, Magnus Hellström, and Jonas Waldenström. “Age and Sex Determination of Mallards Anas Platyrhynchos in Autumn”. Ornis Svecica 26, no. 2 (April 1, 2016): 61–81. Accessed March 29, 2024. https://journals.lub.lu.se/os/article/view/22530.