%0 Journal Article
%A I. Ts. Gokhberg
%A E. I. Sigal
%T An operator generalization of the logarithmic residue theorem and the theorem of Rouché
%J Sbornik. Mathematics
%D 1971
%P 603-625
%V 13
%N 4
%U http://geodesic.mathdoc.fr/item/SM_1971_13_4_a7/
%G en
%F SM_1971_13_4_a7