@article{DAN_1996_347_3_a2,
     author = {V. V. Volchkov},
     title = {Two-radii theorems on spaces of constant curvature},
     journal = {Doklady Akademii Nauk},
     pages = {300--302},
     publisher = {mathdoc},
     volume = {347},
     number = {3},
     year = {1996},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1996_347_3_a2/}
}