@article{JMPA_1870_2_15__7_0,
     author = {Liouville, J.},
     title = {Extrait d'une {Lettre} adress\'ee \`a {M.} {Besge}},
     journal = {Journal de Math\'ematiques Pures et Appliqu\'ees},
     pages = {7--8},
     volume = {2e s{\'e}rie, 15},
     year = {1870},
     language = {fr},
     url = {http://www.numdam.org/item/JMPA_1870_2_15__7_0/}
}