@article{AM2_1995__50_1-2_137623,
     author = {J\"urg R\"atz and Luigi Paganoni},
     title = {Conditional function equations and orthogonal additivity.},
     journal = {Aequationes mathematicae},
     pages = {135--142},
     publisher = {mathdoc},
     volume = {50},
     number = {1-2},
     year = {1995},
     zbl = {0876.39008},
     url = {http://geodesic.mathdoc.fr/item/AM2_1995__50_1-2_137623/}
}