Ruder, Ken, Bio-Med Grant: Symbolic Play and Language as Developmental Correlates, October 1, 1981-May 31, 1982, Box: 69, Folder: 23. 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/455655 Accessed May 23, 2025.