Shields, Evan M., Jay J. Rotella, and David W. Smith. “Retrospective Analysis of Trumpeter Swan Cygnus Buccinator Decline in Yellowstone National Park, USA”. Wildfowl (November 14, 2024): 89–114. Accessed December 16, 2025. https://tidsskrift.dk/Wildfowl/article/view/161407.