Simak - Untitled collection of short stories (1963), Why Call Them Back From Heaven (1979, 1977, 1971, 1968, 1967, 1966, 1965), Box: 20, Folder: 13. Corporate Papers of the Robert Mills Literary Agency, MS 307. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/230631 Accessed May 15, 2024.