@article{DAN_1957_112_1_a1,
     author = {L. G. Mikhailov},
     title = {The {Riemannian} type of boundary problem for elliptical systems of first order differential equations},
     journal = {Doklady Akademii Nauk},
     pages = {13--15},
     publisher = {mathdoc},
     volume = {112},
     number = {1},
     year = {1957},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1957_112_1_a1/}
}