New Examples of Unicellular Operators Beda Chan Indiana University Mathematics Journal 1983 text pdf 10.1512/iumj.1983.32.32021 10.1512/iumj.1983.32.32021 en Indiana Univ. Math. J. 32 (1983) 241 - 256 state-of-the-art mathematics http://iumj.org/access/