%0 Journal Article %A A. V. Aleksandrov %T The Poincar\'e problem for second-order elliptic systems on a plane in Hardy-type classes %J Differencialʹnye uravneniâ %D 1997 %P 1069-1075 %V 33 %N 8 %I mathdoc %U http://geodesic.mathdoc.fr/item/DE_1997_33_8_a8/ %G ru %F DE_1997_33_8_a8