@article{SM_1975_27_2_a5,
     author = {A. Khatamov},
     title = {On~rational approximations of functions with a~convex derivative},
     journal = {Sbornik. Mathematics},
     pages = {239--250},
     publisher = {mathdoc},
     volume = {27},
     number = {2},
     year = {1975},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1975_27_2_a5/}
}