1. Boundary properties of arbitrary functions;Dolzhenko;Izv. Akad. Nauk. SSSR,1967
2. The spherical derivative of meromorphic functions;Dragosh;J. reine angew. Math.,1972
3. English translation;Math. USSR-Izv.
4. A problem concerning the zeros of a certain kind of holomorphic function in the unit disc;Bagemihl;J. reine angew. Math.,1964