@article{ELMA_1959__14_140697,
     author = {R. Wagner},
     title = {Eindeutige {L\"osungen} der {Funktionalgleichung}  f[x + f(x)] = f(x).},
     journal = {Elemente der Mathematik},
     pages = {73--78},
     publisher = {mathdoc},
     volume = {14},
     year = {1959},
     zbl = {0088.09301},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1959__14_140697/}
}