@article{DAN_1987_297_2_a3,
     author = {A. I. Vol'pert and V. A. Vol'pert},
     title = {Construction of the rotation of the vector field for operators},
     journal = {Doklady Akademii Nauk},
     pages = {280--283},
     publisher = {mathdoc},
     volume = {297},
     number = {2},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1987_297_2_a3/}
}