Reel audio tapes. Barrett talks with Marquis Childs (the latter who was trained under O. K. Bovard); Markham “Media”; “Principles of Persuasion, 19:103. 1963, 1969 [4 tapes; Barrett is not identified on this undated tape, yet Lawrence Barret was a program assistant at Radio WSUI in the early 1960s, and this may refer to him.], 1963-1969, Box: 26. James W. Markham Papers, RG99.0114. University of Iowa Archives. https://aspace.lib.uiowa.edu/repositories/3/archival_objects/413929 Accessed June 19, 2025.