You can start with Hitlers Vienna, the Hitler Biographies by Fest, Machtan, Heiden, Bullock, Uhlrich, Kershaw, Payne, Masur and Shirer; Hitlers Table Talk; the books about the German Post war Revolution by Haffner, Harman, Pelz and Broue; Mein Kampf; once you get those done, you can go to Zitelmann's Hitlers National Socialism.
Let me know when you have those done and I have more.