@article{JMPA_1940_9_19_1-4_307_0,
     author = {Janet, Maurice},
     title = {Sur le probl\`eme de {Pfaff}},
     journal = {Journal de Math\'ematiques Pures et Appliqu\'ees},
     pages = {307--318},
     publisher = {Gauthier-Villars},
     volume = {9e s{\'e}rie, 19},
     number = {1-4},
     year = {1940},
     zbl = {0024.20103},
     language = {fr},
     url = {http://www.numdam.org/item/JMPA_1940_9_19_1-4_307_0/}
}