Jones, Michael L. and Todd R. Risley, An Analysis of Leisure Activity and Materials for Profoundly Mentally Retarded, Multiply Handicapped Persons, March 17, 1981, Box: 45, Folder: 1. 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/454143 Accessed June 26, 2024.