@article{DAN_1976_231_4_a12,
     author = {Yu. V. Bezzubov},
     title = {Observability in problems of one class},
     journal = {Doklady Akademii Nauk},
     pages = {822--825},
     year = {1976},
     volume = {231},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1976_231_4_a12/}
}