The Kac Approach to Potential Theory: Part I. Daniel Stroock Indiana University Mathematics Journal 1967 text pdf 10.1512/iumj.1967.16.16054 10.1512/iumj.1967.16.16054 en Indiana Univ. Math. J. 16 (1967) 829 - 852 state-of-the-art mathematics http://iumj.org/access/