@article{SM_1969_8_2_a5,
     author = {V. L. Levin},
     title = {Application of {E.~Helly's} theorem to convex programming, problems of best approximation and related questions},
     journal = {Sbornik. Mathematics},
     pages = {235--247},
     publisher = {mathdoc},
     volume = {8},
     number = {2},
     year = {1969},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1969_8_2_a5/}
}