Jennings, Collier (November 27, 2024). "Superman #20 review". AIPT Comics. Retrieved December 16, 2024.
archive.org
Tye (2012), p. 243: "Next [Mike Carlin] scribbled on his storyboard "doomsday for Superman". Others chimed in, trying to imagine a villain omnipotent enough to do in Superman and how a world without him would look. By the time they left the room, they had a rough outline for a series of stories. Superman would duke it out with an all-new evil predator who was tearing apart Metropolis. What to call him or it? The answer was there on Carlin's chart: Doomsday". Tye, Larry (2012). Superman: The High-Flying History of America's Most Enduring Hero. Random House New York. ISBN978-1-58836-918-5.
behindthevoiceactors.com
"Doomsday Voices (Superman)". Behind The Voice Actors. A green check mark indicates that a role has been confirmed using a screenshot (or collage of screenshots) of a title's list of voice actors and their respective characters found in its credits or other reliable sources of information.{{cite web}}: CS1 maint: postscript (link)