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.
Information sources often are categorized as primary sources, secondary sources, or tertiary sources according to their originality and/or their proximity to the source or origin of their subject matter; however, the boundaries between these categories are sometimes fuzzy and may differ from discipline to discipline.