There is no copyright date in the book but the contents page is stamped May 6, 1949, as pictured. Dedication note is dated April 1939. Printed in the United States of America.
Upon research, I believe this is a rare first edition. Another first-edition version of this book listed online also excludes a copyright date, has the same cover page, and features the same cipher challenge that was later removed from future editions.
160 pages.
In good condition, but missing original dust jacket. Former property of the New York Public Library, High Bridge Branch.
