Pichugov, S. A. “Asymptotic Behavior of the Best Approximations for the Functions in $L_p$”.
Ukrains’kyi Matematychnyi Zhurnal
45, no. 6 (June 25, 1993): 867–870. Accessed April 11, 2025.
https://umj.imath.kiev.ua/index.php/umj/article/view/5876
.