On sale date from the publication date found at the Catalog of Copyright Entries, Part 2, Periodicals, New Series, Volume 35, January-December 1940, Numbers 1-4. Class B periodical. Copyright number B 448920.
On sale date confirmed from claimed use date with the title trademark submission to U.S. Patent and Trademark Office from the Official Gazette of the United States Patent Office. Volume 488, March 1938 (March 1), page 21. Listings of published trademarks. Trademark serial number 400,982, David McKay Company, Philadelphia, Pennsylvania. Filed December 17, 1937. Ace Comics. For periodical publication. Claims use since March 3, 1937.