@article{DE_1985_21_6_a12,
     author = {A. B. Vasil'eva and M. A. Petrova},
     title = {Periodic solutions of singularly perturbed equations of elliptic type},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1013--1020},
     publisher = {mathdoc},
     volume = {21},
     number = {6},
     year = {1985},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1985_21_6_a12/}
}