@article{AM2_1985__28_137053,
     author = {Peter Volkmann and Lutz Volkmann},
     title = {\"Uber die {Charakterisierung} der {Funktion} f(x) = x durch {Funktionalgleichungen,} {I.}},
     journal = {Aequationes mathematicae},
     pages = {151--155},
     publisher = {mathdoc},
     volume = {28},
     year = {1985},
     zbl = {0561.39002},
     url = {http://geodesic.mathdoc.fr/item/AM2_1985__28_137053/}
}