What's the matter with Nazis?
Or, more accurately, what's so difficult about doing efficient, quality research regards to the Nationalsozialistische Deutsche Arbeiterpartei (NSDAP)? One problem is that this area of history attracts a great deal of nonprofessional & partisan research which lacks serious academic rigor. There are other fields in history that are similar in this respect: piracy or the American Civil War are two typical examples.
This guide will assist you in this endeavor. One of the best methods is to use resources available through the Auraria Library. Academic libraries tend to offer access to academic materials. That alone will eliminate many irrelevant or unacceptable sources.