초록
We show that the condition S of Sidon is sufficient for the integrability of the limit of Rees-$Stanojevi{\acute{c}$ cosine sums $g_n(x)={\frac{1}{2}}{\limits\sum^{n}_{k=0}}{\Delta}a_k+{\limits\sum^{n}_{k=1}}{\limits\sum^{n}_{j=k}}{\Delta}a_j\;cos\;kx$.