References
- J. K. Beem, P. E. Ehrlich, and K. L. Easley, Global Lorentzian Geometry, 2nd edition, Dekker, New York, 1996.
- A. N. Bernal and M. Sanchez, On smooth Cauchy hypersurfaces and Geroch's splitting theorem, Comm. Math. Phys. 243 (2003), no. 3, 461-470. https://doi.org/10.1007/s00220-003-0982-6
- A. N. Bernal and M. Sanchez, Smoothness of time functions and the metric splitting of globally hyperbolic spacetimes, Comm. Math. Phys. 257 (2005), no. 1, 43-50. https://doi.org/10.1007/s00220-005-1346-1
- E. Minguzzi and M. Sanchez, The causal hierarchy of spacetimes, arxiv:gr-qc/0609119.
- B. O'Neill, Semi-Riemannian Geometry with Applications to Relativity, Pure and Applied ser., Vol. 103, Academic Press, New York, 1983.
- R. Penrose, Techniques of Differential Topology in Relativity, Regional Conference Series in Applied Mathematics, Vol. 7, SIAM Publications, Philadelphia, 1972.