Abel and Riesz Transforms of Series Having Bounded Partial Sums Ralph Agnew Indiana University Mathematics Journal 1954 text pdf 10.1512/iumj.1954.3.53003 10.1512/iumj.1954.3.53003 en Indiana Univ. Math. J. 3 (1954) 47 - 72 state-of-the-art mathematics http://iumj.org/access/