1. S. N. Bernstein,Collected Works (Publ. Soviet Acad., 1954) (Russian).
2. A. Zygmund,Trigonometric series (Cambridge, 1959).
3. P. O. H. Vértesi, On the convergence of Hermite-Fejér interpolation,Acta Math. Acad. Sci. Hung.,22 (1971), pp. 151–158.
4. S. B. Stechkin, On the approximation of periodic functions by Fejér-sums,Trudy Mat. Inst. Steklov,62 (1961), pp. 48–60 (Russian).
5. A. F. Timan,Theory of approximation of functions of real variables (Moscow, 1960) (Russian).