The Spherical Representations of Groups Transitive on S^n R. Smith Indiana University Mathematics Journal 1975 text pdf 10.1512/iumj.1975.24.24028 10.1512/iumj.1975.24.24028 en Indiana Univ. Math. J. 24 (1975) 307 - 325 state-of-the-art mathematics http://iumj.org/access/