Collects Thor (1966) #337-340.
*The hammer, Mjolnir, supreme weapon of the gods, was forged in the smithies of the dwarves and enchanted by the Allfather Odin. His spell decreed that "Whosoever holds this hammer, if he be worthy, shall possess the power of Thor." None save Thor, son of Odin and god of thunder, has ever held Mjolnir and possessed its matchless power. None... till now. *Source: Back Cover