Edgar Loftin advised that the M-DIS logo on the cover is for Mcfadden Distributors. (I believe he is referring to Bernarr Mcfadden.)
Bob Hughes added that the black North American continent symbol between the letter M (on its left) and the letters DIS (on its right) refers to Independent Distributors of North America. See his http://dccomicsartists.com/dchistory/DCHISTORY-2.htm
Previous indexer credited Al Fago with cover art but that is not his distinctive signature (also, that's a V surrounding the "Fago" name).
Woolfolk credit from Martin O'Hearn, as per http://martinohearn.blogspot.com/
Woolfolk credit from Martin O'Hearn, as per http://martinohearn.blogspot.com/