William Patrick Wilson, Antiquarian Books [Peacock Books catalog, 2002, found laid in back cover], Box: 85, Folder: 1. 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/205188 Accessed June 02, 2024.