Normal Operators on the Banach Space L^p (-\infty,\infty) Part II: Unbounded Operators Gregers Krabbe Indiana University Mathematics Journal 1961 text pdf 10.1512/iumj.1961.10.10008 10.1512/iumj.1961.10.10008 en Indiana Univ. Math. J. 10 (1961) 111 - 133 state-of-the-art mathematics http://iumj.org/access/