@article{DA_2013_20_1_a7,
     author = {V. V. Shenmaier},
     title = {The smallest $k$-enclosing ball problem},
     journal = {Diskretnyj analiz i issledovanie operacij},
     pages = {93--99},
     publisher = {mathdoc},
     volume = {20},
     number = {1},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DA_2013_20_1_a7/}
}