@article{DAN_1991_321_3_a11,
     author = {M. A. Krasnosel'skii and J. Moven and A. V. Pokrovskii},
     title = {New theorems on forced periodic oscillations and bounded},
     journal = {Doklady Akademii Nauk},
     pages = {491--495},
     publisher = {mathdoc},
     volume = {321},
     number = {3},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1991_321_3_a11/}
}