Found on the inside front cover.
The last page's strip is dated 8/29/37.
The third page is dated 4-7-40; the fourth page is dated 1-7-40.
The "Stratosphere Jim and His Flying Fortress" feature formerly appeared in Crackajack Funnies (Western, 1938 Series), but is now moving to Super Comics.
The first strip is dated 6-29-39; the last one is dated 7-25-39.
Found on inside back cover.