Zimmer, Ayer Library ["Catalog of the Edward E. Ayer Ornithological Library"], Box: 26, Folder: 18. Sauer's Gouldiana Research about John Gould and other papers, MS 304. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/204875 Accessed February 26, 2025.