@article{ASNSP_1987_4_14_4_527_0, author = {Franchi, B. and Serapioni, R.}, title = {Pointwise estimates for a class of strongly degenerate elliptic operators : a geometrical approach}, journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze}, pages = {527--568}, publisher = {Scuola normale superiore}, volume = {Ser. 4, 14}, number = {4}, year = {1987}, mrnumber = {963489}, zbl = {0685.35046}, language = {en}, url = {http://www.numdam.org./item/ASNSP_1987_4_14_4_527_0/} }