Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DAN_1971_198_6_a6, author = {S. I. Pokhozhaev}, title = {On periodic solutions of some nonlinear hyperbolic equations}, journal = {Doklady Akademii Nauk}, pages = {1274--1277}, publisher = {mathdoc}, volume = {198}, number = {6}, year = {1971}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1971_198_6_a6/} }
S. I. Pokhozhaev. On periodic solutions of some nonlinear hyperbolic equations. Doklady Akademii Nauk, Tome 198 (1971) no. 6, pp. 1274-1277. http://geodesic.mathdoc.fr/item/DAN_1971_198_6_a6/