@article{ASENS_1866_1_3__7_0,
     author = {Stephan, E.},
     title = {Sur une classe d'\'equations aux d\'eriv\'ees partielles du second ordre},
     journal = {Annales scientifiques de l'\'Ecole Normale Sup\'erieure},
     pages = {7--53},
     publisher = {Elsevier},
     volume = {1e s{\'e}rie, 3},
     year = {1866},
     doi = {10.24033/asens.18},
     language = {fr},
     url = {http://archive.numdam.org/articles/10.24033/asens.18/}
}