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/).
On the page between page 2 and page 3 of the previous story sequence.
Letters from Peter Stern, Alex Lotocki, Alexander Varias, Deborah Bassett, Jimmy Zaenglein, Gregory Urquhart, James Norvelle, Jesse C. Walter, and Douglas C. Farson.
Surprise Feature
Publisher: National Periodical Publications
575 Lexington Ave, NY, NY 10022
Editor: Mort Weisinger
Owners: Harry Donenfeld, Jack Liebowitz; P Sampliner; Irwin Donenfeld, S Sampliner, Sonia Iger.
No circulation figures