@article{SM_1994_79_1_a10,
     author = {Ya. Sh. Il'yasov},
     title = {On the existence of periodic solutions of semilinear elliptic equations},
     journal = {Sbornik. Mathematics},
     pages = {167--178},
     publisher = {mathdoc},
     volume = {79},
     number = {1},
     year = {1994},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1994_79_1_a10/}
}