Action Comics #291

Red Kryptonite causes Superman to no longer be vulnerable to Green Kryptonite, but he is now vulnerable to other everyday objects. Supermen of America ad. Superman Krypton ad. 1st meeting of Supergirl and Mr. Mxyzptlk in "The Bride of Mr. Mxyzptlk!", script by Jerry Siegel, art by Jim Mooney; Mr. Mxyzptlk decides to pester Supergirl while Superman is away from Earth, so he first changes many people into Bizarros and then restores Supergirl's Kryptonian parents to life, before deciding that Supergirl should marry him.