1. Askey, R., Remarks on the Preceding Paper by Gavin Brown and Edwin Hewitt, Math. Ann., 268(1984), 123–126.
2. Askey, R., Vietoris’s Inequalities and Hypergeometric Series, Recent progress in Inequalities (Niš, 1996), Math. Appl., 430, 63–76, Kluwer Acad. Publ., Dordrecht, 1998.
3. Askey, R., Some Positive Trigonometric Sums, Trans Amer Math Soc, 187(1974), 295–307.
4. Belov, A. S., On the Coefficients of Trigonometric Series with Nonnegative Partial Sums, Mat. Zametki, 41(1987), 152–158.
5. Brown, G., Dai, F. and Wang, K., Extensions of Vietoris’s Inequalities I, Advances in Mathematics (China), 34:1(2005), 125–127.