@article{ZVMMF_1971_11_4_a4,
     author = {B. M. Budak and E. M. Berkovich},
     title = {On the approximation of extremal {problems.~II}},
     journal = {\v{Z}urnal vy\v{c}islitelʹnoj matematiki i matemati\v{c}eskoj fiziki},
     pages = {870--884},
     publisher = {mathdoc},
     volume = {11},
     number = {4},
     year = {1971},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZVMMF_1971_11_4_a4/}
}