@article{JMPA_1936_9_15__42_0,
     author = {Cartan, \'Elie},
     title = {La g\'eom\'etrie de l'int\'egrale $\int F \left(x, y, y', y'' \right) dx$},
     journal = {Journal de Math\'ematiques Pures et Appliqu\'ees},
     pages = {42--69},
     publisher = {Gauthier-Villars},
     volume = {9e s{\'e}rie, 15},
     year = {1936},
     zbl = {0014.36801},
     language = {fr},
     url = {http://archive.numdam.org/item/JMPA_1936_9_15__42_0/}
}