Ridgway, Roger [includes book: "Ridgway's Hummingbirds"], Box: 22, Folder: 56-57. 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/204815 Accessed February 26, 2025.