@article{CMH_1984__59_139995,
     author = {Jean-Pierre Serre},
     title = {L'invariant de {Witt} de la forme {Tr(x2).}},
     journal = {Commentarii mathematici Helvetici},
     pages = {651--676},
     publisher = {mathdoc},
     volume = {59},
     year = {1984},
     zbl = {0565.12014},
     url = {http://geodesic.mathdoc.fr/item/CMH_1984__59_139995/}
}