"The best presentation of the general theory [of relativity] is still Eddington's book of 1923, The Mathematical Theory of Relativity. For the planetary motion and the motion of the moon, see: de Sitter, "On Einstein's theory of gravitation and and its astronomical consequences," Monthly Notices, R. Astr. Soc. London, 76:699; 77:155. The mathematical foundation, the calculus of tensors, is given very completely in Eddington's book. For an exhaustive treatment see: Levi-Cevita, The Absolute Differential Calculus, translated by Dr. E. Perisco (1927)."