Singular Integral Equations, Boundary Value Problems and the Riemann-Roch Theorem Walter Koppelman Indiana University Mathematics Journal 1961 text pdf 10.1512/iumj.1961.10.10017 10.1512/iumj.1961.10.10017 en Indiana Univ. Math. J. 10 (1961) 247 - 277 state-of-the-art mathematics http://iumj.org/access/