@article{DAN_1958_122_4_a3,
     author = {S. L. Sobolev},
     title = {On mixed problems for partial differential equations with two independent variables},
     journal = {Doklady Akademii Nauk},
     pages = {555--558},
     publisher = {mathdoc},
     volume = {122},
     number = {4},
     year = {1958},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1958_122_4_a3/}
}