@article{GDZPPN002207338,
title = {Pfister's conjecture on quadratic Co-fields.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {405},
year = {1990},
pages = {209-220},
zbl = {0685.10014},
url = {http://dml.mathdoc.fr/item/GDZPPN002207338}
}
Leep, David B. Pfister's conjecture on quadratic Co-fields.. Journal für die reine und angewandte Mathematik, Tome 405 (1990) pp. 209-220. http://gdmltest.u-ga.fr/item/GDZPPN002207338/