Conformal Invariants of Submanifolds. II C. HsiungJohn Levko Indiana University Mathematics Journal 1988 text pdf 10.1512/iumj.1988.37.37009 10.1512/iumj.1988.37.37009 en Indiana Univ. Math. J. 37 (1988) 181 - 189 state-of-the-art mathematics http://iumj.org/access/