@article{TVP_1993_38_2_a2,
     author = {P. J. Bickel and Y. Ritov},
     title = {Efficient estimation using both direct and indirect observations},
     journal = {Teori\^a vero\^atnostej i ee primeneni\^a},
     pages = {233--258},
     year = {1993},
     volume = {38},
     number = {2},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TVP_1993_38_2_a2/}
}