Look at the figure. The face is a dead giveaway. Compare him to the Adventure 36 and 39 figures. Also the inking. Who else was doing cover work for DC at that same time? Flessel, Guardineer, O'Mealia? There's not enough resemblance to any of them except Flessel, but Flessel has a bolder line and he signs his stuff. Maybe I should edit together cropped images of the faces so that it is easier to see that these covers are done by the same hand. A lot of the problem with identifying Flanagan is that there were so few comics printed with his art. You would have to be a general paper-nerd and have a cross-collection of more than just comics to find some of his other stuff. Check out his non-comic stuff over on Comicartfans.com (Goodhousekeeping, Blue Book, Colliers, etc).