So I am studying for my phd program's qualifying exam and I find that I can solve hardly any of the practice exams from the last 10 years (not able to do any of the problems). I clearly am lacking the basics. Can someone recommend some books to study to get an undergraduate physics level understanding of upper level classical mechanics, E+M, and stat mech/thermal physics? I already own Griffith's quantum mechanics book. All my other text books I sold back to the bookstore. Thanks!