@article{DE_1977_13_7_a24,
     author = {V. S. Mokeichev},
     title = {A criterion for the solvability of certain periodic boundary value problems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1335--1337},
     publisher = {mathdoc},
     volume = {13},
     number = {7},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1977_13_7_a24/}
}