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2. A. V. Batyrev, “On the question of the best approximation of analytic functions by polynomials,” Dokl. AN SSSR, 76, No. 2, 173–175 (1951).
3. S. N. Bernstein, Extremal Properties of Polynomials [in Russian], ONTI, Moscow–Leningrad, 1937.
4. S. N. Bernstein, “On the best approximation of continuous functions by polynomials of a given degree,” in Collection of Works by S. N. Bernstein [in Russian], Vol. 1, AN SSSR, Moscow, 1952, pp. 11–104.
5. I. K. Daugavet, Introduction to the Theory of Approximation of Functions [in Russian], LGU, Leningrad, 1977.