@article{JMPA_1936_9_15__301_0,
     author = {Vessiot, E.},
     title = {Sur les faisceaux de transformations infinit\'esimales associ\'es aux \'equations aux d\'eriv\'ees partielles du second ordre $\mathrm{F} \left(x, y, z, p, q, r, s, t\right) = o$},
     journal = {Journal de Math\'ematiques Pures et Appliqu\'ees},
     pages = {301--320},
     publisher = {Gauthier-Villars},
     volume = {9e s{\'e}rie, 15},
     year = {1936},
     zbl = {0015.21005},
     language = {fr},
     url = {http://archive.numdam.org/item/JMPA_1936_9_15__301_0/}
}