Solovyeva, Diana, and Sergey Vartanyan. “Aspects of the Breeding Biology of Bewick’s Swans Cygnus Columbianus Bewickii Nesting in High Densities in the Chaun River Delta, Chukotka, East Russia”. Wildfowl, Nov. 2014, p. 148–166, https://tidsskrift.dk/Wildfowl/article/view/153625.