Isometries of the Nevanlinna Class Kenneth Stephenson Indiana University Mathematics Journal 1977 text pdf 10.1512/iumj.1977.26.26023 10.1512/iumj.1977.26.26023 en Indiana Univ. Math. J. 26 (1977) 307 - 324 state-of-the-art mathematics http://iumj.org/access/