P. - "Geological map of U.S." (1893)

P. - "Geological map of U.S." (1893), Box: 17-A, Folder: 42. A River Running West literary archive, RH MS 981. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/320941 Accessed December 25, 2025.