Integral Operators on L^p Spaces, Part II Walter Schachermayer Indiana University Mathematics Journal 1981 text pdf 10.1512/iumj.1981.30.30020 10.1512/iumj.1981.30.30020 en Indiana Univ. Math. J. 30 (1981) 261 - 266 state-of-the-art mathematics http://iumj.org/access/