%0 Journal Article %A Ya. V. Bykov %A R. Kabulov %T The periodic oscillations with large amplitude of certain classes of nonlinear systems %J Differencialʹnye uravneniâ %D 1972 %P 223-229 %V 8 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/DE_1972_8_2_a2/ %G ru %F DE_1972_8_2_a2