Continuous boundary values of conformal maps

Let $G$ be a bounded simply connected domain in the complex plane. A point $a\in \partial G$ is said to be accessible from inside of $G$ if there is a Jordan arc $J$ such that $J\subset \bar G$ and $J\cap\partial G=\{a\}$. In this paper the author shows that a univalent analytic function $\psi$ from the unit disk $D$ onto $G$ extends continuously to $\bar D$ if and only if every $a\in\partial G$ is accessible. The main result covers a famous theorem proved by C. Carathe\"{o}dory, which says that if $G$ is a Jordan domain, then $\psi$ extends to be a homeomorphism from $\bar D$ onto to $\bar G$.