The Comass Ball in \Lambda^3(R^6)* Reese HarveyFrank Morgan Indiana University Mathematics Journal 1986 text pdf 10.1512/iumj.1986.35.35007 10.1512/iumj.1986.35.35007 en Indiana Univ. Math. J. 35 (1986) 145 - 156 state-of-the-art mathematics http://iumj.org/access/