Graham, Donna. "Fox Squirrel (Sciurus niger)". Northern State University. South Dakota Department of Game, Fish and Parks. Archived from the original on 2013-01-11. Retrieved 2013-12-07.
Graham, Donna. "Fox Squirrel (Sciurus niger)". Northern State University. South Dakota Department of Game, Fish and Parks. Archived from the original on 2013-01-11. Retrieved 2013-12-07.