@article{DAN_1981_256_4_a1,
     author = {I. A. Ibragimov and R. Z. Khas'minskii},
     title = {On some problems of nonparametric estimation of the value of a linear functional},
     journal = {Doklady Akademii Nauk},
     pages = {781--783},
     publisher = {mathdoc},
     volume = {256},
     number = {4},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1981_256_4_a1/}
}