@article{MZ_1978__162_172720,
     author = {H. Silvermann and E.M. Silvia and D. Telage},
     title = {Convolution {Conditions} for {Convexity,} {Starlikeness} and {Spiral-Likeness.}},
     journal = {Mathematische Zeitschrift},
     pages = {125--130},
     publisher = {mathdoc},
     volume = {162},
     year = {1978},
     zbl = {0369.30004},
     url = {http://geodesic.mathdoc.fr/item/MZ_1978__162_172720/}
}