Melnik YI. Inverse theorems of approximation of regular (in convex polygons) functions by exponential polynomials in the integral metric. Ukr. Mat. Zhurn. [Internet]. 1988 Nov. 1 [cited 2025 Dec. 5];40(6):751-7. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/9285