Von Haake, A.,  and United States. Post Office Dept.  "Post route map of the state of South Dakota showing post offices with the intermediate distances on mail routes in operation on the 1st of December, 1903."  Map.  1903.  Norman B. Leventhal Map & Education Center,  https://collections.leventhalmap.org/search/commonwealth:cj82kn284 (accessed May 29, 2020).