@article{DAN_1960_133_1_a1,
     author = {A. I. Vol'pert},
     title = {The index of boundary value problems for systems of harmonic functions in three independent variables},
     journal = {Doklady Akademii Nauk},
     pages = {13--15},
     publisher = {mathdoc},
     volume = {133},
     number = {1},
     year = {1960},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1960_133_1_a1/}
}