Gotaas, Geir, Eric Milne, Paul Haggarty, and TylerNicholas J.C. “Energy Expenditure of Free-Living Reindeer Estimated by the Doubly Labelled Water Method”. Rangifer 20, no. 4 (March 1, 2000): 211-219. Accessed December 14, 2019. https://septentrio.uit.no/index.php/rangifer/article/view/1516.