USDA Circular 917, Relation of Cultural Practices to Winter Wheat Production, Southern Great Plains Field Station, Woodward, Oklahoma, June 1953, Box: 26, Folder: 29. Frank A. Theis papers, RH MS 948. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/61040 Accessed July 12, 2025.