Program Project, Communication Research with Retarded Children, D. M. Baer formerly Joseph Spradlin, HD-00870-17,September 27, 1979, Box: 60, Folder: 15. 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/455385 Accessed July 09, 2025.