@article{AIHPC_2009__26_1_285_0,
     author = {Wang, Qian},
     title = {On the {Geometry} of {Null} {Cones} in {Einstein-Vacuum} {Spacetimes}},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {285--328},
     publisher = {Elsevier},
     volume = {26},
     number = {1},
     year = {2009},
     doi = {10.1016/j.anihpc.2008.03.002},
     mrnumber = {2483823},
     zbl = {1157.83309},
     language = {en},
     url = {http://www.numdam.org/articles/10.1016/j.anihpc.2008.03.002/}
}