1. [BP1] Betori, W., Plagliacci, M.: Harmonic analysis for groups acting on trees. Boll. Unione Mat. Ital. (6)3-B, 333?345 (1984)
2. [BP2] Betori, W., Pagliacci, M.: The Radon transform on trees. Boll. Unione Mat. Ital (6)5-B, 267?277 (1986)
3. Lectures notes in Math.;P. Cartier,1973
4. [C2] Cartier, P.: Fonctions harmoniques sur un arbre. Symp. Math.9, 203?207 (1972)
5. [C3] Cartier, P.: Harmonic analysis on trees, Proc. Symp. Pure Math. A.M.S.26, 419?424 (1972)