| Issue | #400 |
| Published | May 1971 |
| Cover Price | 0.15 |
| Pages | 36 |
| Editing | Murray Boltinoff |
| Characters | Superman; Gregor Nagy |
| Genre | superhero |
| Pencils | Neal Adams |
| Inks | Dick Giordano |
| Reprinted | in Superman From the Thirties to the Eighties (Crown Publishers, Inc., 1983 series) #nn |
| Characters | Superman; Gregor Nagy [The Changeling]; Jan Nagy |
| Genre | superhero |
| Script | Leo Dorfman |
| Pencils | Curt Swan |
| Inks | Murphy Anderson |
| Reprinted | in Superman (Egmont Ehapa, 1966 Series) #6/1981 |
| Letters | typeset |
| Notes | Includes a letter from Bob Rozakis. |
| Characters | Superman; Supergirl; Brainiac; Yllura; Arvor; Kandor |
| Genre | superhero |
| Script | Leo Dorfman [as Geoff Browne] |
| Pencils | Curt Swan |
| Inks | Murphy Anderson |
| Notes | Takes place in Kandor. |
| Reprinted | in Superman From the Thirties to the Seventies (Crown Publishers, Inc., 1971 series) #nn (1971) |