Comet: Stories of Super Time and Space. Springfield, Mass.: H-K Publications, Inc., December 1940

Comet: Stories of Super Time and Space. Springfield, Mass.: H-K Publications, Inc., December 1940, Volume: Gilbert C536. Robert L. Gilbert First Issues collection, Gilbert. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/525536 Accessed December 27, 2025.