@article{DAN_1971_197_5_a6,
     author = {M. I. Kokotov},
     title = {Almost-periodicity of solutions of the equation $\partial^2u/\partial t^2=\Delta u-q(x)u+f(x,t)$},
     journal = {Doklady Akademii Nauk},
     pages = {1014--1017},
     publisher = {mathdoc},
     volume = {197},
     number = {5},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1971_197_5_a6/}
}