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.
Primary sources are the first hand evidence left behind by participants or observers at the time of events. Primary sources originate in the time period that historians are studying. They vary a great deal.
For a historical research project, secondary sources are generally scholarly books and articles. A secondary source interprets and analyzes primary sources. These sources are one or more steps removed from the event. Secondary sources may contain pictures, quotes or graphics of primary sources. Some types of secondary source include: Textbooks; journal articles; histories; criticisms; commentaries; encyclopedias. Examples of secondary sources include: A scholarly journal article about the history of cardiology.