@article{MAN_1891__39_157569,
     author = {E. Picard},
     title = {Sur les formes quadratiques \`a ind\'etermin\'ees conjug\'ees. {(Extrait} d'une lettre adressee \`a {Mr.} {F.} {Klein).}},
     journal = {Mathematische Annalen},
     pages = {142--144},
     publisher = {mathdoc},
     volume = {39},
     year = {1891},
     language = {fr},
     url = {http://geodesic.mathdoc.fr/item/MAN_1891__39_157569/}
}