@article{ASENS_1900_3_17__211_0,
     author = {Cotton, \'Emile},
     title = {Sur les invariants diff\'erentiels de quelques \'equations lin\'eaires aux d\'eriv\'ees partielles du second ordre},
     journal = {Annales scientifiques de l'\'Ecole Normale Sup\'erieure},
     pages = {211--244},
     publisher = {Elsevier},
     volume = {3e s{\'e}rie, 17},
     year = {1900},
     doi = {10.24033/asens.480},
     language = {fr},
     url = {http://www.numdam.org/articles/10.24033/asens.480/}
}