@article{DAN_1976_226_4_a2,
     author = {B. A. Bubnov},
     title = {Boundary value problems for a symmetric system of first-order equations},
     journal = {Doklady Akademii Nauk},
     pages = {753--756},
     publisher = {mathdoc},
     volume = {226},
     number = {4},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1976_226_4_a2/}
}