@article{AM2_1997__53_1-2_137682,
     author = {L\'aszl\'o Losonczi},
     title = {A structure theorem for sum form functional equations.},
     journal = {Aequationes mathematicae},
     pages = {141--154},
     publisher = {mathdoc},
     volume = {53},
     number = {1-2},
     year = {1997},
     zbl = {0869.39008},
     url = {http://geodesic.mathdoc.fr/item/AM2_1997__53_1-2_137682/}
}