Colombo, John, Individual Differences in Early Visual Behavior, Correspondence File, 1986 - 1989, Box: 12, Folder: 25. 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/452535 Accessed July 09, 2025.