%0 Journal Article
%A A. A. Bel'kovich
%T On the existence of invariant tori for a periodic Hamiltonian system having some of characteristic indices with nonzero real part
%J Differencialʹnye uravneniâ
%D 1987
%P 192-198
%V 23
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DE_1987_23_2_a1/
%G ru
%F DE_1987_23_2_a1