@article{MAN_1978__234_163132,
     author = {J\'on Kr. Arason and Manfred Knebusch},
     title = {\"Uber die {Grade} quadratischer {Formen.}},
     journal = {Mathematische Annalen},
     pages = {167--192},
     year = {1978},
     volume = {234},
     zbl = {0362.10021},
     url = {http://geodesic.mathdoc.fr/item/MAN_1978__234_163132/}
}