@article{DE_1969_5_9_a2,
     author = {Ya. V. Bykov and T. Chinkaraev},
     title = {The periodic vibrations of nonlinear systems with resonance. {I}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1558--1574},
     publisher = {mathdoc},
     volume = {5},
     number = {9},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1969_5_9_a2/}
}