%0 Journal Article
%A J. William Helton
%A Igor Klep
%A Scott McCullough
%T The tracial Hahn–Banach theorem, polar duals, matrix convex sets, and projections of free spectrahedra
%J Journal of the European Mathematical Society
%D 2017
%P 1845-1897
%V 19
%N 6
%I mathdoc
%U http://geodesic.mathdoc.fr/articles/10.4171/jems/707/
%R 10.4171/jems/707
%F JEMS_2017_19_6_a5