XVIII. Special and General Principle of Relativity
XIX. The Gravitational Field
XX. The Equality of Inertial and Gravitational Mass as an Argument for the General Postulate of Relativity
XXI. In What Respects are the Foundations of Classical Mechanics and of the Special Theory of Relativity Unsatisfactory?
XXII. A Few Inferences from the General Principle of Relativity
XXIII. Behaviour of Clocks and Measuring-Rods on a Rotating Body of Reference
XXIV. Euclidean and non-Euclidean Continuum
XXV. Gaussian Co-ordinates
XXVI. The Space-Time Continuum of the Special Theory of Relativity Considered as a Euclidean Continuum
XXVII. The Space-Time Continuum of the General Theory of Relativity is Not a Euclidean Continuum
XXVIII. Exact Formulation of the General Principle of Relativity
XXIX. The Solution of the Problem of Gravitation on the Basis of the General Principle of Relativity