"On the Concept of Man", Proceedings of the Seventh Inter-American Congress of Philosophy, vol. II, pp. 55-61, 1967, Box: 13, Folder: 14. Personal papers of Richard T. De George, PP 531. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/315347 Accessed June 16, 2025.