@article{TM_1992_194_a13,
     author = {I. V. Petrova},
     title = {Approximation on a~hyperboloid in the $L_2$-metric},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {215--228},
     publisher = {mathdoc},
     volume = {194},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1992_194_a13/}
}