A Functional Calculus for Hyponormal Operators Roger Howe Indiana University Mathematics Journal 1974 text pdf 10.1512/iumj.1974.23.23054 10.1512/iumj.1974.23.23054 en Indiana Univ. Math. J. 23 (1974) 631 - 644 state-of-the-art mathematics http://iumj.org/access/