This book, easy to find on the collector market, is under-rated as a reference for a study of early NSDAP uniforms, insignia, flags, etc.  This is literally an archive of information on the early years of the party.  This example is the "post-Röhm" version, and is in outstanding collection (many have severely broken spines).  Light wear, markings to the cover, but fully intact with all printed photo-cards present.