@incollection{JEDP_1988____A1_0, author = {Richard Beals}, title = {Calcul pseudodiff\'erentiel trois-\'etape}, booktitle = {}, series = {Journ\'ees \'equations aux d\'eriv\'ees partielles}, eid = {1}, pages = {1--4}, publisher = {\'Ecole polytechnique}, year = {1988}, zbl = {0661.35020}, mrnumber = {975490}, language = {fr}, url = {https://proceedings.centre-mersenne.org/item/JEDP_1988____A1_0/} }