1. The causal hierarchy of spacetimes;Minguzzi,2008
2. Global Lorentzian Geometry;Beem,1996
3. Techniques of Differential Topology in Relativity;Penrose,1972
4. Semi-Riemannian Geometry with Applications to Relativity;O’Neill,1983
5. The Large Scale Structure of Space-Time;Hawking,1973