Heiner, Heidi Anne (16 April 2008). "Buttercup". SurLaLune Fairy Tales: The Fairy Tales of Asbjørnsen and Moe. Archived from the original on 5 April 2014.
Heiner, Heidi Anne (16 April 2008). "Buttercup". SurLaLune Fairy Tales: The Fairy Tales of Asbjørnsen and Moe. Archived from the original on 5 April 2014.