@article{DE_1968_4_8_a3,
     author = {A. E. Gel'man},
     title = {The approximate determination of periodic modes in high frequency processes},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1396--1403},
     publisher = {mathdoc},
     volume = {4},
     number = {8},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1968_4_8_a3/}
}