KONOHRAI, A. F.; STASYUK, S. A. Best <i>M</i>-term trigonometric approximations of the classes of periodic functions of many variables in the space <i>L<sub>q</sub&gt;. Ukrains’kyi Matematychnyi Zhurnal, v. 60, n. 9, p. 1196 -, 25 Sep. 2008.