The Boundary Behavior of a Quasi-Conformal Mapping A. Lohwater Indiana University Mathematics Journal 1956 text pdf 10.1512/iumj.1956.5.55012 10.1512/iumj.1956.5.55012 en Indiana Univ. Math. J. 5 (1956) 335 - 342 state-of-the-art mathematics http://iumj.org/access/