Hello all. I am self teaching physics, and after completing Classical Mechanics (Special Relativity included), Classical EM and an introductory course to QM, I would like to take a very introductory look to General Relativity. With this purpose in mind, I have chosen 2 books, and I would like to buy one of them: 1) Gron - Naess "Einsteins Theory for the mathematically untrained". 2) Collier "A most incomprehensible thing". I have taken a look to both of them, and I have seen that they follow quite different approaches. Collier seems to be more "ordered" (fiist the basis of needed mathemathics, then Newtonian gravitation, Special relativity, Manifolds, curvature, Einstein's equations, etc.) while Gron introduces all this concepts as needed. Besides, Gron does not even metion thing like "manifolds", "one-forms", etc. (I guess he uses them anyway, but with different names, maybe). On the other hand, Gron is a physics teacher specilized in GR, so I guess his book must be more rigorous. I wonder if anyone could suggest me which of these books is best suited, or has better expplanations. Thanks in advance.