New York Botanical Garden. [Charles] Darwin to [Edwin] Prince letter, 1839-01-21, Box: 14, Folder: 36. 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/205801 Accessed June 26, 2024.