@article{DE_1998_34_2_a13,
     author = {T. I. Kiguradze},
     title = {On doubly periodic solutions of a class of nonlinear hyperbolic equations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {238--245},
     year = {1998},
     volume = {34},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1998_34_2_a13/}
}