Serdyuk, A. S. (2002). Approximation of Periodic Analytic Functions by Interpolation Trigonometric Polynomials in the Metric of the Space $L$.
Ukrains’kyi Matematychnyi Zhurnal,
54(5), 692-699.
https://umj.imath.kiev.ua/index.php/umj/article/view/4108