@article{DE_1981_17_3_a5,
     author = {G. V. Zhidkov},
     title = {Inequalities for differential operators from algebraic polynomials on the sphere},
     journal = {Differencialʹnye uravneni\^a},
     pages = {479--487},
     publisher = {mathdoc},
     volume = {17},
     number = {3},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1981_17_3_a5/}
}