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• G. Das, Anasuya Nath and B.K Ray, An estimate of the rate of convergence of Fourier series in the generalized Holder metric, Narosa Publishing House, New Delhi, India (2002) pp. 43-60.
• R. Salem and A. Zygmund, Capacity of sets and Fourier series, Trans. Amer. Math. Soc. 59 (1946), pp. 23-41.
• A. Zygmund, Trigonometric series, Volumes I and II combined, Cambridge University Press, New York, 1993.