Letter from son-in-law Osborn Duke, January 11, 1976, with 4 color photographs of Hays beetle model; also pencil sketch, Box: 1, Folder: 5. Russell Randolph Hays papers, RH MS 564. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/278069 Accessed May 06, 2024.