StasyukS. A. “Best <i>M</i>-Term Orthogonal Trigonometric Approximations of the Classes <i>B</i><sup> Ω</sup><sub>p,θ</sub&gt; Of Periodic Functions of Many Variables”. Ukrains’kyi Matematychnyi Zhurnal 60, no. 5 (May 25, 2008): 647 -. Accessed November 23, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3183.