Graphs and figures showing world climate change in relation to commodities [copies from a book], 600 B.C.-1940 A.D, Box: 2 (oversize), Folder: 3-4. Personal Papers of Raymond H. Wheeler, PP 217. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/188273 Accessed April 23, 2025.