@article{DE_1984_20_2_a2,
     author = {A. I. Bulgakov and B. A. Sergeev},
     title = {Oscillatory properties of solutions of a nonlinear system of second-order ordinary differential equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {207--214},
     publisher = {mathdoc},
     volume = {20},
     number = {2},
     year = {1984},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1984_20_2_a2/}
}