@article{MAN_1880__16_156888,
     author = {Ptaszychi},
     title = {Extrait d'une lettre \`a {M.C.Neumann}},
     journal = {Mathematische Annalen},
     pages = {264--266},
     publisher = {mathdoc},
     volume = {16},
     year = {1880},
     url = {http://geodesic.mathdoc.fr/item/MAN_1880__16_156888/}
}