10 drawings of Hays inventions [untitled, n.d.] (from envelope labeled "Older Pat[ented] Material, 1960s"), Box: 8, Folder: 14. Russell Randolph Hays papers, RH MS 564. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/278222 Accessed May 08, 2024.