%0 Journal Article
%A Peter Hess
%A Tosio Kato
%T Perturbation of Closed Operators and Their Adjoints.
%J Commentarii mathematici Helvetici
%D 1970
%P 524-529
%V 45
%I mathdoc
%U http://geodesic.mathdoc.fr/item/CMH_1970__45_139455/
%F CMH_1970__45_139455