“…The absolute convergence and summability of multiple Fourier series and integrals and also of more general expansions have been investigated in [54,56,85,98,125,128,157,164,181,198,206,221,222,223,234,237,327,[362][363][364][365][366]376,383,384,419,446,462]. (0 = @ l f + ty) as,v (y), 9 9 N while the integration is taken over the surface of the unit sphere S N, then N--1…”