Triangular Integration on Symmetrically Normed Ideals J. Erdos Indiana University Mathematics Journal 1978 text pdf 10.1512/iumj.1978.27.27029 10.1512/iumj.1978.27.27029 en Indiana Univ. Math. J. 27 (1978) 401 - 408 state-of-the-art mathematics http://iumj.org/access/