@article{DAN_1967_174_1_a8,
     author = {B. T. Polyak},
     title = {A general method for solving extremal problems},
     journal = {Doklady Akademii Nauk},
     pages = {33--36},
     year = {1967},
     volume = {174},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1967_174_1_a8/}
}