@article{MZM_1999_65_3_a4,
     author = {E. V. Petrova},
     title = {The number and stability of nonlinear parametric oscillations in a~system of weakly coupled oscillators with pendulum nonlinearity},
     journal = {Matemati\v{c}eskie zametki},
     pages = {369--376},
     publisher = {mathdoc},
     volume = {65},
     number = {3},
     year = {1999},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1999_65_3_a4/}
}