%0 Journal Article %A V. O. Kuznetsov %T On properties of associated quadratic differentials in some extremal problems %J Zapiski Nauchnykh Seminarov POMI %D 1988 %P 85-97 %V 168 %I mathdoc %U http://geodesic.mathdoc.fr/item/ZNSL_1988_168_a7/ %G ru %F ZNSL_1988_168_a7