@article{JEDP_1982____A15_0, author = {Stein, Elias M.}, title = {An example of the {Heisenberg} group}, journal = {Journ\'ees \'equations aux d\'eriv\'ees partielles}, eid = {15}, publisher = {Ecole polytechnique}, year = {1982}, zbl = {0497.35069}, language = {en}, url = {http://archive.numdam.org/item/JEDP_1982____A15_0/} }