@article{AM2_1979__19_136840,
     author = {Walter Benz},
     title = {On the functional equation ... {(Short} {Communication).}},
     journal = {Aequationes mathematicae},
     pages = {313--314},
     publisher = {mathdoc},
     volume = {19},
     year = {1979},
     url = {http://geodesic.mathdoc.fr/item/AM2_1979__19_136840/}
}