@article{MZM_1999_65_3_a16,
     author = {T. Yu. Kulikova},
     title = {On the approximation of functions by a~hyperbolic angle in the $L_2$ metric},
     journal = {Matemati\v{c}eskie zametki},
     pages = {471--474},
     publisher = {mathdoc},
     volume = {65},
     number = {3},
     year = {1999},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1999_65_3_a16/}
}