@article{GDZPPN002434350, title = {On the Angular Derivative of Analytic Functions.}, journal = {Mathematische Zeitschrift}, volume = {194}, year = {1987}, pages = {591-601}, zbl = {0616.30033}, url = {http://dml.mathdoc.fr/item/GDZPPN002434350} }
Gnuschke-Hauschild, D. On the Angular Derivative of Analytic Functions.. Mathematische Zeitschrift, Tome 194 (1987) pp. 591-601. http://gdmltest.u-ga.fr/item/GDZPPN002434350/