@article{DAN_1969_189_3_a11,
     author = {M. I. \`Eskin},
     title = {A boundary value problem for an overdetermined system of two second order equations},
     journal = {Doklady Akademii Nauk},
     pages = {491--494},
     publisher = {mathdoc},
     volume = {189},
     number = {3},
     year = {1969},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1969_189_3_a11/}
}