@article{AM2_1989__38_1_137317,
     author = {J. R\"atz and Gy. Szab\'o},
     title = {On orthogonally additive mappings, {IV.}},
     journal = {Aequationes mathematicae},
     pages = {73--85},
     publisher = {mathdoc},
     volume = {38},
     number = {1},
     year = {1989},
     zbl = {0679.39005},
     url = {http://geodesic.mathdoc.fr/item/AM2_1989__38_1_137317/}
}