Issue has a gatefold cover (not on the original).
On-sale date from comiclist.com.
from Secret Origins (DC, 1961 series) #1 (Summer 1961)
from Detective Comics (DC, 1937 series) #225 (November 1955) [John Jones vignette]
from Showcase (DC, 1956 series) #4 (September-October 1956) [Flash vignette]
from World's Finest Comics (DC, 1941 series) #94 (May-June 1958) [Superman, Batman & Robin vignette]
from Mystery in Space (DC, 1951 series) #53 (August 1959) [Adam Strange vignette]
from World's Finest Comics (DC, 1941 series) #94 (May-June 1958)Silver-Age team origin
from Showcase (DC, 1956 series) #17 (November-December 1958)Origin and 1st appearance Adam Strange
from Green Lantern (DC, 1960 series) #1 (July-August 1960)Origin recap.
from Showcase (DC, 1956 series) #6 (January-February 1957)Origin and 1st appearance of Challengers. Partial reprint.
from Secret Origins (DC, 1961 series) #1 (Summer 1961)Text story with two small illustrations.
from Wonder Woman (DC, 1942 series) #105 (April 1959), #105 (April 1959)Silver-Age origin.
from Detective Comics (DC, 1937 series) #225 (November 1955)Origin and 1st appearance J'Onn J'Onzz.
Script (only) attributed to Jack Miller by Rich Morrissey, but disputed by Bob Hughes. Samachson is current DC credit, as seen in Showcase Presents: Martian Manhunter (DC, 2007 series) #1.
from Showcase (DC, 1956 series) #4 (September-October 1956)Origin and 1st appearance Flash