@article{DAN_1962_143_5_a2,
     author = {A. V. Bitsadze},
     title = {Equations of mixed type in three-dimensional regions},
     journal = {Doklady Akademii Nauk},
     pages = {1017--1019},
     publisher = {mathdoc},
     volume = {143},
     number = {5},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1962_143_5_a2/}
}