@article{DAN_1991_320_4_a17,
     author = {Yu. E. Anikonov},
     title = {Formulas in inverse problems for second-order equations},
     journal = {Doklady Akademii Nauk},
     pages = {848--850},
     publisher = {mathdoc},
     volume = {320},
     number = {4},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1991_320_4_a17/}
}