@article{TM_1984_166_a13,
     author = {S. M. Nikol'skii and P. I. Lizorkin},
     title = {Approximation by spherical polynomials},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {186--200},
     year = {1984},
     volume = {166},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1984_166_a13/}
}