@article{CMH_1949__23_138989,
     author = {Aurel Wintner},
     title = {On {Implicit} {Analytic} {Systems.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {294--302},
     year = {1949},
     volume = {23},
     zbl = {0035.17201},
     url = {http://geodesic.mathdoc.fr/item/CMH_1949__23_138989/}
}