@article{10_4153_CMB_1963_034_1,
     author = {Penry, M. D.},
     title = {Composition {Theorems} on {Dirichlet} {Series}},
     journal = {Canadian mathematical bulletin},
     pages = {397--403},
     year = {1963},
     volume = {6},
     number = {3},
     doi = {10.4153/CMB-1963-034-1},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1963-034-1/}
}