"State gasoline taxes," by Edmund P. Learned, Bulletin of the University of Kansas, v. 26, no. 6 (March 15, 1925), Box: 1, item: 2. Stanley Learned Collection, RH MS 831. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/106753 Accessed April 27, 2024.