Boiko, Dmitrijs, and Leho Luigujõe. “Distribution, Abundance and Habitat Choice of Whooper Swans Cygnus Cygnus Breeding in Latvia and Estonia, 1973–2021”. Wildfowl (November 14, 2024): 266–278. Accessed December 16, 2025. https://tidsskrift.dk/Wildfowl/article/view/156363.