Hello everyone, First of all, I am a third year undergraduate student. I have just finished studying (on my own) Sakurai' s "Modern Quantum Mechanics" (and I have done almost all exercises). I have taken courses in Complex Analysis (contour integration, residues etc) and in PDE (unfortunately this course did not cover Green Functions). I want to proceed to QFT. I took also a course on Special Relativity, at the level of Rindler. I am currently studying (on my own again) GR from Weinberg. I tried to tackle Relativistic QM from Bjorken & Drell. However, I could not understand how the covariance of the Dirac equation was proven. I know nothing about group theory and I suppose I need to learn some before going into QFT. I plan on studying from Wu-Ki Tung and Georgi. I saw also a nice chapter about the representation of the Lorentz and Poincaré group in Greiner (Relativistic Quantum Mechanics). Now my question: Is it really necessary to master all these topics, i.e. RQM and group theory before starting QFT? Should I go through all of Georgi for example? Do you have any other good book (and preferably not too long) to suggest me? I would appreciate some help! Thanks!