@article{DAN_1993_331_5_a5,
     author = {I. A. Ibragimov and V. Kherdle and A. B. Tsybakov},
     title = {Efficient estimation of an averaged derivative},
     journal = {Doklady Akademii Nauk},
     pages = {550--552},
     publisher = {mathdoc},
     volume = {331},
     number = {5},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1993_331_5_a5/}
}