Rudy's finger is pointing to a post-it indicates that this is a message. Book was written in 1939.
Hitler initiated PLAN Z in 1939.
January 27 – Adolf Hitler orders Plan Z, a 5-year naval expansion programme intended to provide for a huge German fleet capable of crushing the Royal Navy by 1944. The Kriegsmarine is given the first priority on the allotment of German economic resources.
https://en.wikipedia.org/wiki/1939
Rudolph first appeared in a 1939 booklet written by Robert L. May and published by Montgomery Ward, the department store.[1][2][3]
https://en.wikipedia.org/wiki/Rudolph_the_Red-Nosed_Reindeer