Introduction to the Theory of Relativity by Peter Gabriel Bergmann
Comprehensive coverage of the special theory (frames of reference, Lorentz transformation, relativistic mechanics of mass points, more), the general theory (principle of equivalence, Riemann-Christoffel curvature tensor, more) and the unified theory (Weyl's gauge-invariant geometry, Kaluza's five-dimensional theory and projective field theories, more.)
Dover Publications, 1976.
ISBN: 9780486632827. 307 pp.
Foreword by Albert Einstein.
Softcover. Very good.