In the letter column for World's Finest Comics #239, Jack C. Harris explains that the head shot of Superman in the banner is from Justice League of America #76 (Nov/Dec, 1969) and that the pose of Atom in the banner is from The Atom #26 (Aug/Sep, 1966).
Story in four parts: splash page (1 page with overall story title), Part 1 The Germ People (6 pp.), Part 2 Mission to Very Small Universe (6 pp.), Part 3 Shall a Child Live? (5 pp.).
Letters of comment from Brian D. Scott, Kevin Ferris, Mike Bates, Mal Mancin, Michael D. Dargay, Thomas Mahoney, David Seidman, Robert Watson, Mannie Zweigel and John Hooper.