%0 Journal Article
%A M. Sh. Birman
%T Average procedure for periodic operators near an edge of internal gap
%J Algebra i analiz
%D 2003
%P 61-71
%V 15
%N 4
%I mathdoc
%U http://geodesic.mathdoc.fr/item/AA_2003_15_4_a1/
%G ru
%F AA_2003_15_4_a1