On Para-Unicellular Operator Algebras Avraham Feintuch Indiana University Mathematics Journal 1974 text pdf 10.1512/iumj.1974.23.23047 10.1512/iumj.1974.23.23047 en Indiana Univ. Math. J. 23 (1974) 567 - 573 state-of-the-art mathematics http://iumj.org/access/