@article{DAN_1988_303_1_a4,
     author = {E. N. Makhmudov},
     title = {Necessary conditions for problems of optimal control that are},
     journal = {Doklady Akademii Nauk},
     pages = {29--33},
     publisher = {mathdoc},
     volume = {303},
     number = {1},
     year = {1988},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1988_303_1_a4/}
}