Art submitted on May 21, 1962. Barks only did the art on the cover, the idea came from someone else.
Art submitted on April 12, 1962. Art for this story was published without any panel borders of any kind. Synopsis from "Carl Barks and the Art of the Comic Book" by Michael Barrier (M. Lilien, 1981).
Art submitted on April 18, 1962. Panels are published with strips of color as panel borders, reducing the size of the art. Synopsis from "Carl Barks and the Art of the Comic Book" by Michael Barrier (M. Lilien, 1981).
Same as front cover without the logo and trade dress.