@article{DAN_1991_317_1_a0,
     author = {S. A. Vakhrameev},
     title = {The {Morse} index theorem for extremals of some optimal control},
     journal = {Doklady Akademii Nauk},
     pages = {11--15},
     publisher = {mathdoc},
     volume = {317},
     number = {1},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1991_317_1_a0/}
}