Extensions in the Applicability of Riemann's Formula G. Ludford Indiana University Mathematics Journal 1954 text pdf 10.1512/iumj.1954.3.53005 10.1512/iumj.1954.3.53005 en Indiana Univ. Math. J. 3 (1954) 77 - 88 state-of-the-art mathematics http://iumj.org/access/