Söderholm, Svan. “Does the Pochard Aythya Ferina Vary periodically?—an Analysis of Census Data from Angarnsjöängen, Sweden 1978—2003 and Lake Engure, Latvia 1972—1992”. Ornis Svecica 16, no. 3 (July 1, 2006): 85–94. Accessed April 24, 2024. https://journals.lub.lu.se/os/article/view/22712.