Notarized typescripts of high frequency whistle test results: sound wave recycling (conducted 1980), wave trains (conducted 1973), resonator reruns (conducted 1973), Box: 9, Folder: 7. Russell Randolph Hays papers, RH MS 564. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/278240 Accessed May 06, 2024.