@article{IM_1996__123_3_144349,
     author = {Thomas C. Sideris},
     title = {The null condition and global existence of nonlinear elsastic waves.},
     journal = {Inventiones mathematicae},
     pages = {323--342},
     publisher = {mathdoc},
     volume = {123},
     number = {3},
     year = {1996},
     zbl = {0844.73016},
     url = {http://geodesic.mathdoc.fr/item/IM_1996__123_3_144349/}
}