@article{DAN_1958_120_3_a4,
     author = {G. E. Kuzmak},
     title = {Asymptotic solutions of the equation of motion for a non-linear oscillatory system having one degree of freedom},
     journal = {Doklady Akademii Nauk},
     pages = {461--464},
     year = {1958},
     volume = {120},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1958_120_3_a4/}
}