I'm a physics major and I'm pretty sure that I want to go into theoretical physics research. Due to scheduling difficulties and such, I haven't been able to systematically study math. I'm am very comfortable with all the basic math that any physics major should know - multivariable calc, PDEs, linear algebra, complex analysis (Riemann sheets, Cauchy integration techniques etc..), tensors, a little bit of group theory...I have also worked enough with differential geometry and topology since I do gravitational physics research. I want to fill the gaps in my math education by reading books (rigorous, challenging ones) and teaching myself things that I probably missed. I have been following the MIT open courseware site, but since I do have a time constraint, I was wondering which topics I must focus on and which books/lecture notes are good for them (considering that I would like these topics to give me greater insight into physics.) I don't know if this matters, but I am deciding between theoretical condensed matter physics and high energy theory. Thanks!