Anita Singh (13 de diciembre de 2011). «Frozen Planet polar bear died in Dutch zoo». The Daily Telegraph(en inglés). Consultado el 19 de abril de 2019. «the smaller of the twins, who was named Swimmer and was underweight at birth, died in March 2010, three months after the scenes were shot.
The larger cub, Walker, was shipped to the Highland Wildlife Park in Kincraig, Scotland».
