@article{TM_1986_173_a14,
     author = {P. I. Lizorkin and S. M. Nikol'skii},
     title = {Approximation by spherical functions},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {181--189},
     publisher = {mathdoc},
     volume = {173},
     year = {1986},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1986_173_a14/}
}