1. John A . Simpson Papers, Western History Collections, University of Oklahoma, Norman.
2. Brotherhood of Railway and Steamship Clerks, Freight Handlers, Express and Station Employees. Proceedings of the Eleventh Regular and Third Triennial Convention of the Brotherhood of Railway and Steamship Clerks, Freight Handlers, Express and Station Employees, n.p., 1922.
3. South Dakota Bankers Association. Report of the Twenty-ninth Annual Convention of the South Dakota Bankers Association, n.p., 1920.
4. American Farm Bureau Federation. Proceedings of the 17th Annual Convention of the American Farm Bureau Federation, n.p., 1935.
5. Wall Street Journal