@article{DAN_1978_242_6_a3,
     author = {R. A. Polyak},
     title = {On finding a fixed point of a class of set-valued mappings},
     journal = {Doklady Akademii Nauk},
     pages = {1252--1255},
     publisher = {mathdoc},
     volume = {242},
     number = {6},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1978_242_6_a3/}
}