Hoyt and Fulton, Stimulus Control in Operant Audiometry, PRH 233201, Correspondence, 1972, Box: 44, Folder: 26. University of Kansas Schiefelbusch Institute for Life Span Studies records, RG 35. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/454113 Accessed June 26, 2024.