Lists of rotor tests and rotor patents and patent applications filed by Hays 1930 to 1945, with 3 rotor drawings [from envelope labeled "Aircraft patents, 1935-1945"], Box: 5, Folder: 6. Russell Randolph Hays papers, RH MS 564. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/278157 Accessed May 05, 2024.