@article{IM2_1992_38_1_a4,
     author = {I. A. Kuzin},
     title = {Existence of a countable set of periodic, spherically symmetric solutions of a~nonlinear wave equation},
     journal = {Izvestiya. Mathematics},
     pages = {107--129},
     year = {1992},
     volume = {38},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1992_38_1_a4/}
}