%0 Journal Article %A L. A. Kalyakin %T On the problem of first correction in soliton perturbation theory %J Sbornik. Mathematics %D 1995 %P 977-1002 %V 186 %N 7 %I mathdoc %U http://geodesic.mathdoc.fr/item/SM_1995_186_7_a4/ %G en %F SM_1995_186_7_a4