1. M.S. Morris, K.S. Thorne, Amer. J. Phys. 56, 395 (1988)
2. L. Flamm, Phys. Z. 17, 448 (1916)
3. C.W. Misner et al., Gravitation (Princeton University Press, New Jersey, USA, 2017)
4. A. Einstein, N. Rosen, Phys. Rev. 48, 73 (1935)
5. H. Weyl, Philosophy of Mathematics and Natural Science (Princeton University Press, New Jersey, USA, 1949)