This graduate-level text extends beyond mathematical derivations to elaborate on physical ideas underlying relativity, with a historical introduction and examinations of special theory (space-time transformations, four-dimensional formulations, mechanics, optics, electromagnetism), and general theory (space-time continuum, gravitation, experiments, and relativistic cosmology). 1974 edition. Unabridged republication of the second edition published by Pergamon Press, Oxford, 1974.
Here's a sample of other books in this Dover category
The Principle of Relativity by Albert Einstein, Francis A. Davis Eleven papers that forged the general and special theories of relativity include seven papers by Einstein, two by Lorentz, and one each by Minkowski and Weyl. 1923 edition.
Theory of Relativity by W. Pauli Nobel Laureate's brilliant early treatise on Einstein's theory consists of his original 1921 text plus retrospective comments 35 years later. Concise and comprehensive, it pays special attention to unified field theories.
Space, Time, Matter by Hermann Weyl Excellent introduction probes deeply into Euclidean space, Riemann's space, Einstein's general relativity, gravitational waves and energy, and laws of conservation. "A classic of physics." — British Journal for Philosophy and Science.
General Relativity and Gravitational Waves by J. Weber Concise introduction by a pioneer in the investigation of gravitational waves explains the related Riemannian geometry and tensor calculus, conservation laws, and classic experiments. 1961 edition.
The Principle of Relativity with Applications to Physical Science by Alfred North Whitehead The distinguished English mathematician, philosopher presents an alternative rendering of the theory of relativity, conceived long after Einstein's original groundbreaking papers; appropriate for upper-level undergraduates and graduate students. 1922 edition.