@article{MZ_1982__180_173211,
     author = {J\"org Winkler and Sakari Toppila},
     title = {On the {Spherical} {Derivative} of a {Meromorphic} {Function} with a {Valiron} {Deficient} {Value.}},
     journal = {Mathematische Zeitschrift},
     pages = {545--552},
     year = {1982},
     volume = {180},
     zbl = {0498.30035},
     url = {http://geodesic.mathdoc.fr/item/MZ_1982__180_173211/}
}