Dr. C. S. Turnbull, 1847-1918
- "U.S. Geological Survey Photographic Library," U.S. Geological Survey Photographic Library, 1871, accessed November 21, 2012, photo by W. H. Jackson. http://libraryphoto.cr.usgs.gov/htmllib/batch05/batch05j/batch05z/batch05/jwh01121.jpg
- F. V. Hayden, Preliminary Report of The United States Geological Survey of Montana and Portions of Adjacent Territories; Being A Fifth Annual Report of Progress (Washington: Government Printing Office, 1872), pg. 4.