Program Project, Communication Research with Retarded Children, Joseph Spradlin, September 25, 1978, Box: 60, Folder: 12. 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/455382 Accessed May 17, 2025.