%0 Journal Article
%A J. Mennicke
%A J. Elstrodt
%A F. Grunewald
%T Kloosterman sums for Clifford algebras and a lower bound for the positive eigenvalues of the Laplacian for congruence subgroups acting on hyperbolic spaces.
%J Inventiones mathematicae
%D 1990
%P 641-686
%V 101
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/IM_1990__101_2_143820/
%F IM_1990__101_2_143820