%0 Journal Article %A Mauceri, Giancarlo %T Riesz means for the eigenfunction expansions for a class of hypo-elliptic differential operators %J Annales de l'Institut Fourier %D 1981 %P 115-140 %V 31 %N 4 %I Institut Fourier %U https://doi.org/10.5802/aif.851 %R 10.5802/aif.851 %G en %F AIF_1981__31_4_115_0