Possible Hubbell inks per Nick Caputo via the GCD Error List (November 2006). Nick has examined the art at his blog:
http://nick-caputo.blogspot.com/2014/06/the-unknown-art-of-carl-hubbell.ht…
Original indexer credited Dick Ayers.
Letters from Jim Irving, Ray Torres, and Alvin Grimes; includes The Mighty Marvel Checklist and announcement of Kid Colt Annual which was not published.