@article{DAN_1963_148_5_a10,
     author = {Ya. A. Roitberg and Z. G. Sheftel},
     title = {General boundary-value problems for elliptic equations with discontinuous coefficients},
     journal = {Doklady Akademii Nauk},
     pages = {1034--1037},
     publisher = {mathdoc},
     volume = {148},
     number = {5},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1963_148_5_a10/}
}