This is my go to website for pretty much nearly everything National Socialism. I love the website because it contains an array of various books, speeches, art, music and much more. The website has different languages available, however, not everything is available in other languages other than German so do look out for that. The German language section naturally has the most abundant material, which is what I use because I speak German, and then the English section has a lot too.
Feel free to browse and see what you like.