@article{DAN_1960_133_3_a3,
     author = {V. N. Karp},
     title = {The existence and uniqueness of a periodic solution of a non-linear problem concerning the forced vibrations of a string},
     journal = {Doklady Akademii Nauk},
     pages = {515--518},
     publisher = {mathdoc},
     volume = {133},
     number = {3},
     year = {1960},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1960_133_3_a3/}
}