StasyukS. A. (2008). 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(5), 647 -. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/3183