Well, I have been about two years without studying almost anything. I am going to start a thesis about three dimensional spaces (need to understand and explain their isometries, curvature, geodesics), the eight spaces or manifolds, BUT when I try to start I realized I am completely lost, I used to be a good student.
So, what topics do I need to revies, study and understand in order to start my thesis? If you have recommended books that also helps.
Thanks.