@article{DE_1988_24_7_a27,
     author = {M. A. Petrova and I. A. Shishmarev},
     title = {Periodic solutions of partial differential equations with small parameters},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1276--1278},
     publisher = {mathdoc},
     volume = {24},
     number = {7},
     year = {1988},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1988_24_7_a27/}
}