The exponential transform: a renormalized Riesz potential at critical exponent Bjorn GustafssonMihai Putinar 31C0544-9944A1253C65 Indiana University Mathematics Journal 2003 text pdf 10.1512/iumj.2003.52.2304 10.1512/iumj.2003.52.2304 en Indiana Univ. Math. J. 52 (2003) 527 - 568 state-of-the-art mathematics http://iumj.org/access/