Unander , Sigmund, Atle Mortensen, and Arve Elvebakk. “Seasonal Changes in Crop Content of the Svalbard Ptarmigan Lagopus Mutus Hyperboreus”. Polar Research 3, no. 2 (January 12, 1985): 239-245. Accessed April 3, 2026. https://polarresearch.net/index.php/polar/article/view/2528.