Justice League of America, Vol. 1 #213 (1982)

Into The Microcosmos, Into The Microcosmos!
Hawkman tells the Justice League of how he was contacted by Jean Loring, The Atom's wife, over her concerns about the Atom's state of mind. Confronting the Atom, Hawkman is dismayed at the emotional state he finds his friend in and tries to help before the Atom vanishes from a machine in his lab, travelling into the Microcosmos. The League travel to Atom's lab and use the same machine to follow the Atom, shrinking themselves until they land in a strange world and quickly discover they have no memory of who they are. Finding a native - the Wanderer - they realise at least that they search for a friend before they are attacked by Devil Guards of Goltha. The Wanderer takes them to Ch'anar where they find the citadel of Goltha which bears the same symbol as that of the Atom and has done for a hundred years.
Release Date: 1982