Method of Characteristics for Self-Gravitating Anisentropic Relativistic Compressible Fluids G. Saini Indiana University Mathematics Journal 1961 text pdf 10.1512/iumj.1961.10.10015 10.1512/iumj.1961.10.10015 en Indiana Univ. Math. J. 10 (1961) 223 - 231 state-of-the-art mathematics http://iumj.org/access/