I recently graduated from High School (or Sweden's equivalent). I am entering quite a difficult university program studying physics / math in a couple of months. I am interested in self-studying this summer simply because I find the subjects fascinating, especially the mathematical side of it. However, I don't know how to proceed. What should I learn with knowledge of high school physics and maths? What is the typical roadmap to understanding quantum-mechanics and other high-level physics or developing extraordinary math skills? I have all the time in the world right this summer. Are there any good books / websites etc? Thank you.