On Weinstein's Intermediate Problems for Integral Equations with Difference Kernels Ivar Stakgold Indiana University Mathematics Journal 1970 text pdf 10.1512/iumj.1970.19.19028 10.1512/iumj.1970.19.19028 en Indiana Univ. Math. J. 19 (1970) 301 - 307 state-of-the-art mathematics http://iumj.org/access/