@article{DAN_1957_114_3_a2,
     author = {A. I. Vol'pert},
     title = {Investigation of boundary problems for elliptical systems of differential equations on a plane},
     journal = {Doklady Akademii Nauk},
     pages = {462--464},
     publisher = {mathdoc},
     volume = {114},
     number = {3},
     year = {1957},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1957_114_3_a2/}
}