Program Project, Communication Research with Retarded Children, Joseph Spradlin, September 28, 1977, Box: 60, Folder: 11. 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/455381 Accessed May 18, 2025.