@article{AM2_1985__29_137076,
     author = {Frantisek Neumann},
     title = {A vector functional equation and linear differential equations.},
     journal = {Aequationes mathematicae},
     pages = {19--23},
     year = {1985},
     volume = {29},
     zbl = {0593.39006},
     url = {http://geodesic.mathdoc.fr/item/AM2_1985__29_137076/}
}