On approximation of functions by trigonometric polynomials with incomplete spectrum in $L_p$, $0<p<1$

Suppose $B$ is a subset of integers that possesses certain arithmetic properties. Estimates of the best approximation of functions in the space $L_p$, $0<p<1$, by trigonometric polynomials that are constructed by the system $\{e^{ikx}\}_{k\in\mathbb Z\setminus B}$ are obtained. Bibl. – 13 titles.