Risley, Todd, Exploratory Behavior of the Profoundly Multi-Handicapped, June 23, 1981, Box: 68, Folder: 3. 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/455597 Accessed May 20, 2025.