%0 Journal Article %A Patrick Brosnan %A Zinovy Reichstein %A Angelo Vistoli %T Essential dimension, spinor groups, and quadratic forms %J Annals of mathematics %D 2010 %P 533-544 %V 171 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4007/annals.2010.171.533/ %R 10.4007/annals.2010.171.533 %G en %F 10_4007_annals_2010_171_533