More after the break.
Category: Supergirl
Action Comics #268 Sept. 1960
How can there be two Supergirls on Earth? Is it the result of red Kryptonite or maybe a robot? Oh, I got it! How about a red Kryptonite-powered robot?
Action Comics #267 August 1960
Action Comics #264 May 1960
Action Comics #265 June 1960
What would lead Supergirl to break her promise to her cousin and reveal her existence to the world? One thing is guaranteed: it either involves 1) aliens 2) robots 3) kryptonite or 4) super-hypnosis.