R.L. Allen Coal Co. advertisment laid in between pages 182 and 183, The New Knowledge by K.U. Professor R.K. Duncan, Box: 6, Folder: 10. Personal papers of E.H.S. Bailey, PP 158. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/116361 Accessed May 16, 2024.