@article{MZ_1970__116_171382,
     author = {Chung-Chun Yang},
     title = {On {Deficiencies} of {Differential} {Polynomials.}},
     journal = {Mathematische Zeitschrift},
     pages = {197--204},
     publisher = {mathdoc},
     volume = {116},
     year = {1970},
     zbl = {0188.38103},
     url = {http://geodesic.mathdoc.fr/item/MZ_1970__116_171382/}
}