@article{DAN_1963_149_6_a2,
     author = {G. Karatoprakliev},
     title = {On certain boundary-value problems for the equation $u_{xx}+\operatorname{sign}y u_{yy}=0$},
     journal = {Doklady Akademii Nauk},
     pages = {1253--1256},
     publisher = {mathdoc},
     volume = {149},
     number = {6},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1963_149_6_a2/}
}