[Henry] Sotheran - Piccadilly Notes No. 9 [Sauer's notes], Box: 21, Folder: 15. 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/204736 Accessed November 24, 2024.