1.
Romanyuk AS. Approximation of classes of functions of many variables by their orthogonal projections onto subspaces of trigonometric polynomials. Ukr. Mat. Zhurn. [Internet]. 1996Jan.25 [cited 2024Jul.27];48(1):80-9. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/5365