Edgar Loftin advised 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
Ad for Illinois Merchandise Mart
Woolfolk credit from Martin O'Hearn, as per http://martinohearn.blogspot.com/
Woolfolk credit from Martin O'Hearn, as per http://martinohearn.blogspot.com/
Ad for Moon Girl and the Prince (EC, 1947 series) #1
Ad for Blackstone the Magician (EC, 1947 series) #1 and Happy Houlihans (EC, 1947 series) #1
Ad for Illinois Merchandise Mart
Ad for Illinois Merchandise Mart