I used to covet this issue from ads after I started picking up back issues of DCs for a nickel. I wouldn't find a copy of it until the 1980s though!
Ross Andru art on the ad below which appeared often in DC comics of the era.
And on the back cover, probably the most-used ad--alternating with its Norman Rockwell variation--of the Silver Age. I actually sent for the test myself at the end of the decade.