1. Bary, N. K. (1964). A Treatise on Trigonometric Series. Macmillan, New York. https://doi.org/10.1016/C2013-0-08001-2
2. Bari, N. K., & Stechkin, S. B. (1956). Best approximations and differential properties of two conjugate functions. Tr. Mosk. Mat. Obshch., 5, 483–522 (in Russian).
3. Bugrov, Ja. S. (1968). Bernstein type inequalities and their application to the study of differential properties of solutions of differential equations of higher order. Mathematica (Cluj), 5(28), 5–25.
4. Bugrov, Ja. S. (1972). Properties of solutions of differential equations of higher order in terms of weight classes. Trudy Mat. Inst. Steklov., 117, 47–61 (in Russian).
5. Butzer, P., & Nessel, J. R. (1971). Fourier Analysis and Approximation. Birkhauser, Basel. https://doi.org/10.1007/978-3-0348-7448-9