@article{MAN_1980__248_163373,
     author = {Burton Rodin and S.E. Warschawski},
     title = {On the {Derivative} of the {Riemann} {Mapping} {Function} {Near} a {Boundary} {Point} and  the {Visser-Ostrowski} {Problem.}},
     journal = {Mathematische Annalen},
     pages = {125--138},
     publisher = {mathdoc},
     volume = {248},
     year = {1980},
     zbl = {0411.30001},
     url = {http://geodesic.mathdoc.fr/item/MAN_1980__248_163373/}
}