@article{DAN_1965_160_1_a3,
     author = {A. Ya. Dubovitskii and A. A. Milyutin},
     title = {Second variations in extremal problems with constraints},
     journal = {Doklady Akademii Nauk},
     pages = {18--21},
     publisher = {mathdoc},
     volume = {160},
     number = {1},
     year = {1965},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1965_160_1_a3/}
}