The Secret Origin of Superman.
Written by Jerry Siegel, penciled & inked by Joe Shuster.
Reprinted from Action Comics #1.
The Secret Origin of Batman.
Written by Bill Finger, penciled & inked by Bob Kane.
Reprinted from Detective Comics #33.
The Secret Origin of Hawkman "The Ghost".
Written by Bob Kanigher, penciled & inked by Joe Kubert.
Reprinted from Flash Comics #88.
A text article "Secrets of the Secret Origins"
Written by E. Nelson Bridwell.
The Secret Origin of the Flash "Mystery of the Human Thunderbolt!"
Written by Bob Kanigher, penciled by Carmine Infantino, inked by Joe Kubert.
Reprinted from Showcase (Vol 1) #4.