Title: Integrability of Double Power Series with Nonnegative Coefficients
Abstract: We consider the double power series[formula]with coefficientsajk ≥ 0 for alljandk. Among others, we prove exact estimates of certain weightedLp-norms offon the unit square, in terms of the coefficientsajk. Our results extend those of Askey and Boas, Hardy and Littlewood, Khan, Leindler, Mateljević and Pavlović from single to double power series. The further extension to multiple power series is also indicated.