"Mr. Mxyzptlk Voices (Superman)". Behind The Voice Actors. Retrieved November 9, 2023. 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 opening and/or closing credits and/or other reliable sources of information.
Superman #30 at the Grand Comics Database. "Writer credit claimed by Jerry Siegel in a letter to Richard Morrissey that states this story was written prior to earlier printed newspaper sequence by Whitney Ellsworth and Wayne Boring".
