%0 Journal Article
%A Karl-Peter Hadeler
%T Estimates for the spectrum of normal operators
%J Doklady Akademii Nauk
%D 1964
%P 284-287
%V 157
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1964_157_2_a12/
%G ru
%F DAN_1964_157_2_a12