The Kauffman Polynomial and the Two-Fold Cover of a Link Yongwu Rong Indiana University Mathematics Journal 1991 text pdf 10.1512/iumj.1991.40.40016 10.1512/iumj.1991.40.40016 en Indiana Univ. Math. J. 40 (1991) 321 - 331 state-of-the-art mathematics http://iumj.org/access/