On-sale date from copyright registration.
Bob Klein, Gene Reed, Bob Hughes, and Mike Tiefenbacher contend that the pencils are by Dick Dillin and the inks are by Sheldon Moldoff. Craig Delich and Pat Lang contend the art is by Jim Mooney. Letters credit from Todd Klein via his Klein Letters blog (18 September 2016, http://kleinletters.com/Blog/ira-schnapp-in-worlds-finest-comics-part-1/).
Writer credit by Martin O'Hearn.