@article{ASENS_1968_4_1_3_417_0, author = {Goldschmidt, Hubert}, title = {Prolongations of linear partial differential equations. {I.} {A} conjecture of {\'Elie} {Cartan}}, journal = {Annales scientifiques de l'\'Ecole Normale Sup\'erieure}, pages = {417--444}, publisher = {Elsevier}, volume = {Ser. 4, 1}, number = {3}, year = {1968}, doi = {10.24033/asens.1168}, zbl = {0167.09402}, mrnumber = {38 #3888}, language = {en}, url = {http://www.numdam.org/articles/10.24033/asens.1168/} }