@article{DAN_1963_148_4_a2,
     author = {A. V. Bitsadze},
     title = {The homogeneous problem for the directional derivative for harmonic functions in three-dimensional regions},
     journal = {Doklady Akademii Nauk},
     pages = {749--752},
     publisher = {mathdoc},
     volume = {148},
     number = {4},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1963_148_4_a2/}
}