Inverse theorems for approximation of functions regular in convex polygons by exponential polynomials in the integral metric
English version (Springer): Ukrainian Mathematical Journal 40 (1988), no. 6, pp 633-638.
Citation Example: Mel'nik Yu. I. Inverse theorems for approximation of functions regular in convex polygons by exponential polynomials in the integral metric // Ukr. Mat. Zh. - 1988. - 40, № 6. - pp. 751-757.
Full text