@incollection{JEDP_1977____88_0, author = {Bernard Helffer}, title = {Quelques exemples d'op\'erateurs pseudodiff\'erentiels localement r\'esolubles}, booktitle = {}, series = {Journ\'ees \'equations aux d\'eriv\'ees partielles}, pages = {88--116}, publisher = {\'Ecole polytechnique}, year = {1977}, zbl = {0388.47031}, mrnumber = {81g:58035}, language = {fr}, url = {https://proceedings.centre-mersenne.org/item/JEDP_1977____88_0/} }