Exact Solutions of Einstein-Maxwell Equations M. CahenJ. Leroy Indiana University Mathematics Journal 1967 text pdf 10.1512/iumj.1967.16.16034 10.1512/iumj.1967.16.16034 en Indiana Univ. Math. J. 16 (1967) 501 - 508 state-of-the-art mathematics http://iumj.org/access/