4 photostats of lateral drill illustrations and 1 photographic negative (from envelope labeled "Lateral Drill, Photostat Negs, 1948?"), Box: 7, Folder: 11. Russell Randolph Hays papers, RH MS 564. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/278200 Accessed May 05, 2024.