Vlasyk, H. M. “Bernstein – Nikol’skii-Type Inequalities for Trigonometric Polynomials With an arbitrary Choice of Harmonics”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 69, no. 2, Feb. 2017, pp. 147-56, http://umj.imath.kiev.ua/index.php/umj/article/view/1683.