@article{DE_1982_18_6_a15,
     author = {V. F. Butuzov and V. M. Mamonov},
     title = {A singularly perturbed boundary value problem of elliptic type in the critical case},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1056--1061},
     publisher = {mathdoc},
     volume = {18},
     number = {6},
     year = {1982},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1982_18_6_a15/}
}