Story is not signed, but copy that was indexed was autographed by Feldstein, leading to the assumption that he believed it was his work. However, Feldstein in his 2013 biography states that he only inked this issue (and wasn't paid for that).
The pages that appear not to have been done by Feldstein are inked very amateurishly; and while the layouts appear to be by Feldstein, he denies penciling any of this issue (2013).
Appears to be at least somewhat Feldstein's work, but much less refined/finished than the rest of the book.