@article{DAN_1958_122_1_a0,
     author = {I. I. Danilyuk},
     title = {On a problem involving a skew derivative for first order elliptical systems},
     journal = {Doklady Akademii Nauk},
     pages = {9--12},
     publisher = {mathdoc},
     volume = {122},
     number = {1},
     year = {1958},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1958_122_1_a0/}
}