توصیفی شهودی از خمیدگی

[1] S. Carroll, Spacetime and Geometry, Addison Wesley, New York, 2004.
[2] K. F. Gauss, General Investigations of Curved Surfaces of 1827 and 1825, translated by A. Hiltebeitel and J. More-head, The Princeton Library Publishing Association, Princeton, NJ, 1902.
[3] A. Pressley, Elementary Differential Geometry, Springer, London, 2001.
[4] S. Weinberg, Gravitation and Cosmology: Principle and Applications of General Ttheory of Relativity, John Wiley and Sons, New York, 1972.