References
- Graves, L.: Codimension one isometric immersions betweem Lorentzian spaces. Trans. Amer. Math. Soc. 252 (1979), 367-392. https://doi.org/10.1090/S0002-9947-1979-0534127-4
- Graves, L.: On codimension one isometric immersions between indefinite space forms. Tsukuba J. Math. 3 (1979), no. 2, 17-29. https://doi.org/10.21099/tkbjm/1496158685
- Hoffman, D. & R. Osserman: The geometry of the generalized Gauss map. Memoires Amer. Math. Soc. 28, 1980.
- O'Neil, B.: Semi-Riemannian Geometry with application to Relativity. Academic Press, NY, 1983.
- Spivak, M.: Introduction to Differential Geometry IV, Publish or Perish Inc., Berkeley, CA, 1979.