%0 Journal Article
%A K. S. Sibirskii
%T On the number of limit cycles arising from a singular point of focus or center type
%J Doklady Akademii Nauk
%D 1965
%P 304-307
%V 161
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1965_161_2_a12/
%G ru
%F DAN_1965_161_2_a12