@article{DE_1972_8_2_a2,
     author = {Ya. V. Bykov and R. Kabulov},
     title = {The periodic oscillations with large amplitude of certain classes of nonlinear systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {223--229},
     publisher = {mathdoc},
     volume = {8},
     number = {2},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1972_8_2_a2/}
}