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.
Historians use primary sources as the raw evidence to analyze and interpret the past. They publish secondary sources - often scholarly articles or books - that explain their interpretation. When you write a historical research paper, you are creating a secondary source based on your own analysis of primary source material. Examples of primary sources include diaries, journals, speeches, interviews, letters, memos, photographs, videos, public opinion polls, and government records, among many other things.