@article{ZNSL_1993_207_a4,
     author = {I. A. Ibragimov},
     title = {On some problems of nonparametric estimation},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {60--76},
     publisher = {mathdoc},
     volume = {207},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1993_207_a4/}
}