Puppet Master's previous appearance in FANTASTIC FOUR #28 (July 1964); next appearance in FANTASTIC FOUR ANNUAL #3 (November 1965), with his original face incorrectly shown intact. Puppet Master's appearance would remain altered for several years, before he eventually restored his original face.
Part 4 of 17. The sisters in this story apparently served as the inspiration for Craig Russell's later Strange epic, a virtual remake of this story, which he did twice-- in DR. STRANGE ANNUAL #1 (December 1976), and DR. STRANGE: WHAT IS IT THAT DISTURBS YOU, STEVEN? (October 1997).
Letters of comment from Dale Palof; Frank Mastropolo; Joe Hartlaub; and Willie Woodruff, as well as The Mighty Marvel Checklist.