Baer, D. M. and E. B. Herbert, Two Environment Modification of Problem Child Behavior, Submitted, January 26, 1971, Box: 3B, 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/452321 Accessed May 20, 2025.