@article{DAN_1962_146_1_a7,
     author = {B. M. Levitan},
     title = {On the continuation of solutions of partial differential equations},
     journal = {Doklady Akademii Nauk},
     pages = {30--33},
     publisher = {mathdoc},
     volume = {146},
     number = {1},
     year = {1962},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1962_146_1_a7/}
}