Corrections to Discrete Potential Theory and Boundaries J. Doob Indiana University Mathematics Journal 1959 text pdf 10.1512/iumj.1959.8.58063 10.1512/iumj.1959.8.58063 en Indiana Univ. Math. J. 8 (1959) 993 - 993 state-of-the-art mathematics http://iumj.org/access/