@article{DAN_1993_333_6_a5,
     author = {S. R. Umarov},
     title = {Some boundary value problems for elliptic equations with a},
     journal = {Doklady Akademii Nauk},
     pages = {708--710},
     year = {1993},
     volume = {333},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1993_333_6_a5/}
}