@article{DAN_1991_317_3_a17,
     author = {A. A. Tolstonogov},
     title = {Extremal selectors of multivalued mappings and the {\textquotedblleft}bang-bang{\textquotedblright}},
     journal = {Doklady Akademii Nauk},
     pages = {589--593},
     year = {1991},
     volume = {317},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1991_317_3_a17/}
}