@article{MS2_1967__21_166011,
     author = {B.G. Eke},
     title = {On the {Angular} {Derivative} of {Regular} {Functions.}},
     journal = {Mathematica Scandinavica},
     pages = {122--127},
     publisher = {mathdoc},
     volume = {21},
     year = {1967},
     zbl = {0167.06301},
     url = {http://geodesic.mathdoc.fr/item/MS2_1967__21_166011/}
}