@article{DE_1973_9_7_a1,
     author = {Ya. V. Bykov and K. A. Kiriy},
     title = {Periodic oscillations with large {amplitude.~II}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1177--1186},
     publisher = {mathdoc},
     volume = {9},
     number = {7},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1973_9_7_a1/}
}