Note: Haldeman-Julius began printing 3.5 x 5-inch pocket books on cheap paper in 1919. There were several series names before "Little Blue Book" in 1923. --Wikipedia "Titles began appearing as early as 1919, but the Little Blue Books series was not christened until 1923. ... Note that the same issue number was frequently used more than once. Therefore, there are many more Little Blue Books than the 1,915 issue numbers indicate ..." --Debs Collection (IndState.edu)