%0 Journal Article
%A S. Piskarev
%A S.YX. Shaw
%T Pertubation and comparison of cosine operator functions.
%J Semigroup forum
%D 1995
%P 225-246
%V 51
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SF_1995__51_1_135411/
%F SF_1995__51_1_135411