Keith W. Van Etten; Kenneth R. Wilson; Robert L. Crabtree (December 2007). "Habitat Use of Red Foxes in Yellowstone National Park Based on Snow Tracking and Telemetry". Journal of Mammalogy. 88 (6). American Society of Mammalogists: 1498–1507. doi:10.1644/07-mamm-a-076.1. S2CID84936146.
Frank T. van Manen, Mark A. Haroldson, and Bryn E. Karabensh (2018). "Yellowstone Grizzly Bear Investigations 2017: Annual Report of the Interagency Grizzly Bear Study Team" (archive). page 23 (of PDF file). U.S. Geological Survey, Wyoming Game and Fish Department, National Park Service, U.S. Fish and Wildlife Service, Montana Fish, Wildlife and Parks, U.S. Forest Service, Idaho Department of Fish and Game, Eastern Shoshone and Northern Arapaho Tribal Fish and Game Department. Retrieved December 17, 2018.
Keith W. Van Etten; Kenneth R. Wilson; Robert L. Crabtree (December 2007). "Habitat Use of Red Foxes in Yellowstone National Park Based on Snow Tracking and Telemetry". Journal of Mammalogy. 88 (6). American Society of Mammalogists: 1498–1507. doi:10.1644/07-mamm-a-076.1. S2CID84936146.
Frank T. van Manen, Mark A. Haroldson, and Bryn E. Karabensh (2018). "Yellowstone Grizzly Bear Investigations 2017: Annual Report of the Interagency Grizzly Bear Study Team" (archive). page 23 (of PDF file). U.S. Geological Survey, Wyoming Game and Fish Department, National Park Service, U.S. Fish and Wildlife Service, Montana Fish, Wildlife and Parks, U.S. Forest Service, Idaho Department of Fish and Game, Eastern Shoshone and Northern Arapaho Tribal Fish and Game Department. Retrieved December 17, 2018.