Inside front cover. Later also in October 1958 and November 1966 issues.
Letters credit from Todd Klein via his Klein Letters blog (19 September 2016, http://kleinletters.com/Blog/ira-schnapp-in-worlds-finest-comics-part-2/).
Inventory from Danger Trail. However, this story was not part of an ongoing feature.
Inker identification by Craig Delich. Letters credit from Todd Klein via his Klein Letters blog (19 September 2016, http://kleinletters.com/Blog/ira-schnapp-in-worlds-finest-comics-part-2/).