@article{BSMF_1897__25__108_1,
     author = {Beudon, J.},
     title = {Sur les caract\'eristiques des \'equations aux d\'eriv\'ees partielles},
     journal = {Bulletin de la Soci\'et\'e Math\'ematique de France},
     pages = {108--120},
     publisher = {Soci\'et\'e math\'ematique de France},
     volume = {25},
     year = {1897},
     doi = {10.24033/bsmf.557},
     language = {fr},
     url = {http://www.numdam.org/articles/10.24033/bsmf.557/}
}