“Estimates for the Best $M$-Term Trigonometric Approximations of Classes $L_{\beta,p}^\psi$ of Periodic Multivariable Functions in the Case of Small Smoothness in the Space $L_q$”. Transactions of Institute of Mathematics, the NAS of Ukraine, vol. 14, no. 3, Nov. 2017, pp. 293-18, https://trim.imath.kiev.ua/index.php/trim/article/view/324.