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In page Walter Charles Langer:

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After accumulating enough money from publishing a high school textbook titled Psychology and Human Living, Langer traveled to Germany and began working with Anna Freud.[4] Langers time in Germany had overlapped with the historical entrance of Adolf Hitler. As Hitler gained power in Germany, Langer had first-hand experience as to the devastation that was brought to the civilians of the country. Due to his educational background and direct experience, Langer had a personal interest in Adolf Hitler and went to work for the OSS to which he would later predict Hitler's means of death. Langer also continued to produce multiple books in relation to Adolf Hitler after his death, the most notable being The Mind of Adolf Hitler: The Secret Wartime Report.[5]