@article{MZM_2017_101_1_a1,
     author = {A. T. Asanova},
     title = {Periodic {Solutions} in the {Plane} of {Systems} of {Second-Order} {Hyperbolic} {Equations}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {20--30},
     publisher = {mathdoc},
     volume = {101},
     number = {1},
     year = {2017},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2017_101_1_a1/}
}