@article{JMPA_1937_9_16_1-4_251_0,
     author = {Bouligand, Georges},
     title = {Sur les \'equations aux d\'eriv\'ees partielles du premier ordre infiniment voisines d'une \'equation non int\'egrable aux diff\'erentielles totales},
     journal = {Journal de Math\'ematiques Pures et Appliqu\'ees},
     pages = {251--266},
     publisher = {Gauthier-Villars},
     volume = {9e s{\'e}rie, 16},
     number = {1-4},
     year = {1937},
     zbl = {0017.01601},
     language = {fr},
     url = {http://www.numdam.org/item/JMPA_1937_9_16_1-4_251_0/}
}