%0 Journal Article
%A W. Hansen
%T Perturbation of Harmonic Spaces and Construction of Semigroups.
%J Inventiones mathematicae
%D 1973
%P 149-164
%V 19
%I mathdoc
%U http://geodesic.mathdoc.fr/item/IM_1973__19_142192/
%F IM_1973__19_142192