1. Invariant construction of the geometry of a hypersurface of a conformal space;Akivis;Mat. Sb. (N.S.),1952
2. Projective Differential Geometry ofSubmanifolds;Akivis,1993
3. Conformal Differential Geometry and its Generalizations;Akivis,1996
4. Global Lorentzian Geometry;Beem,1996
5. The Mathematical Theory of Black Holes;Chandrasekhar,1983