1. Bochner, S.: Bessel functions and modular relations of higher type and hyperbolic differential equations. Com. Sem. Math. de l'Univ. de Lund 12?20 (1952).
2. Boerner, H.: Representations of groups. Amsterdam: North-Holland Publishing Co. 1963.
3. Gelbart, S.: Stiefel manifold harmonics and generalized Hankel transforms. Bulletin of the A.M.S.78, 451?455 (1972) see also ?A theory of Stiefel harmonics?, to appear.
4. Godement, R.: Seminaire Cartan: Functions automorphes, Institut Poincaré. Paris: Secrétariat mathématique 1958.
5. Notes in Mathematics;K. Gross,1972