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.
A secondary source is one that gives information about a primary source. These sources contain second hand information that has already appeared in primary documents. In this source, the original information is selected, modified and arranged in a suitable format for the purpose of easy location by the users.