Extremal Length and Univalent Functions, I. The Angular Derivative. Burton Rodin; Stefan E. Warschawski — 1977 Mathematische Zeitschrift
Boundary Behavior of the Riemann Mapping Function of Asymptotically Conformal Curves. Stefan E. Warschawski; Frank D. Lesley — 1982 Mathematische Zeitschrift
On Conformal Mappings with Derivative in VMOA. Stefan E. Warschawski; Frank D. Lesley — 1978 Mathematische Zeitschrift