1. H. Baum, Spin structures and Dirac operators on pseudo-Riemannian manifolds,
2. B. Y. Chen, Riemannian submanifolds, In: Handbook of Differential Geometry,
3. B. Y. Chen, Pseudo-Riemannian geometry, δ-invariants and applications, Hackensack,
4. G. R. Eduardo, N. D. Kupeli, Semi-Riemannian maps and their applications,
5. B. O'Neill, Semi-Riemannian geometry with applications to relativity, New