@article{GDZPPN002040751,
title = {Solution of (2, 2)-type sum form functional equations with several unknown functions.},
journal = {Aequationes mathematicae},
volume = {47},
year = {1994},
pages = {191-202},
zbl = {0803.39008},
url = {http://dml.mathdoc.fr/item/GDZPPN002040751}
}
Losonczi, László. Solution of (2, 2)-type sum form functional equations with several unknown functions.. Aequationes mathematicae, Tome 47 (1994) pp. 191-202. http://gdmltest.u-ga.fr/item/GDZPPN002040751/