Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{IM_1990__101_2_143816, author = {D. M\"uller and F. Ricci}, title = {Analysis of second order differential operators on {Heisenberg} groups. {I.}}, journal = {Inventiones mathematicae}, pages = {545--582}, publisher = {mathdoc}, volume = {101}, number = {2}, year = {1990}, zbl = {0742.43006}, url = {http://geodesic.mathdoc.fr/item/IM_1990__101_2_143816/} }
D. Müller; F. Ricci. Analysis of second order differential operators on Heisenberg groups. I.. Inventiones mathematicae, Tome 101 (1990) no. 2, pp. 545-582. http://geodesic.mathdoc.fr/item/IM_1990__101_2_143816/