@article{DAN_1972_202_5_a0,
     author = {V. K. Bel'nov},
     title = {On metric extensions},
     journal = {Doklady Akademii Nauk},
     pages = {991--994},
     publisher = {mathdoc},
     volume = {202},
     number = {5},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1972_202_5_a0/}
}