The Blanchfield pairing of colored links Stefan Friedl Indiana University Mathematics Journal 2018 text pdf 10.1512/iumj.2018.67.7446 10.1512/iumj.2018.67.7446 en Indiana Univ. Math. J. 67 (2018) 2151 - 2180 state-of-the-art mathematics http://iumj.org/access/