On sale date from the publication date reported to the U.S. Copyright Office found in the Catalog of Copyright Entries, Third Series, Volume 15, Part 2, Number 2, Periodicals, July-December 1961. Class B periodical. Copyright registration number B931464. Copyright awarded to National Periodical Publications, Inc. (first issue to do so).
Pencil and ink credits confirmed from Julius Schwartz's editorial records, provided by DC Comics.
Page count confirmed from Julius Schwartz's editorial records, provided by DC Comics. Story in three chapters: unnumbered chapter 1 (6.67 pages), Chapter 2 (6.67 pages), Chapter 3 (10.67 pages); Chapters 2 and 3 with title "Conquerors of Time!".
On the page immediately following page 7 of the main story sequence.
Letters from Richard Weingroff, Geneva Hawkins, Thomas Zmigrocki, Larry Brown, Jeff Reynolds, Albert Romano, Kenneth Drost, Ken Gentry, Edwin M. Eisenberg.
On the two pages immediately following page 14 of the main story sequence.