@article{DAN_1973_208_2_a3,
     author = {\`E. M. Saak},
     title = {On the approximation of solutions to elliptic equations together with derivatives up to the boundary},
     journal = {Doklady Akademii Nauk},
     pages = {277--279},
     publisher = {mathdoc},
     volume = {208},
     number = {2},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_208_2_a3/}
}