Convolution with Oscillating Kernels Per Sjolin Indiana University Mathematics Journal 1981 text pdf 10.1512/iumj.1981.30.30004 10.1512/iumj.1981.30.30004 en Indiana Univ. Math. J. 30 (1981) 47 - 55 state-of-the-art mathematics http://iumj.org/access/