Reduction of Unknowns in Einstein-Maxwell Field Equations III Appendix Vaiclav Hlavaty Indiana University Mathematics Journal 1964 text pdf 10.1512/iumj.1964.13.13053 10.1512/iumj.1964.13.13053 en Indiana Univ. Math. J. 13 (1964) 909 - 926 state-of-the-art mathematics http://iumj.org/access/