The Treaty of Versailles in the mind of the Germans stabbed them in the back, especially the guilt clause that made them take blame for the First World War. Hitler capaitalized on these sentiments and used them to rally the German people.
Secondary Sources are materials that digest, analyze, evaluate and interpret information contained within primary sources or other secondary sources. Examples. 1  Autobiographies, memoirs, diaries, emails, oral histories.  Letters, correspondences, eyewitnesses.
In most cases, they are considered a secondary source. A primary source would be the person the reporter interviewed for the story or a witness who saw the story unfold. Primary sources are contemporary accounts of an event, written by someone who experienced or witnessed the event in question.