MATHEMATICAL INEQUALITIES & APPLICATIONS, vol.8, no.3, pp.521-527, 2005 (SCI-Expanded)
We obtain sufficient conditions for the series E all, which is absolutely summable of order k by a triangular matrix method A, 1 < k <= s < infinity, to be such that Sigma a(n) an is absolutely summable of order s by a triangular matrix B. As corollaries, we obtain a number of inclusion theorems.