On-sale date from copyright registration.
house ad for Superman (DC, 1939 series) #227 [Giant #G-72], on sale April 14
A short feature on Superman's enemies. Art credits from the Best of DC reprint.
Letters from: Jeff Qualls, Arther Harrison, Dave Marr, Bryan Kaster, Alvin Yellon, Gary Kleppe, Ray Fannan, Colin Robertson, and James Mills.
The letter from Colin Robertson suggests that a future child of Saturn Girl and Lightning Lad would be "like Validus of the Fatal Five, able to project mental lightning." This idea was used several years later.