@article{AM2_1976__14_136613,
     author = {John A. Baker},
     title = {On the functional equation f(x) g(y) = p(x+y) q(x/y).},
     journal = {Aequationes mathematicae},
     pages = {493--506},
     publisher = {mathdoc},
     volume = {14},
     year = {1976},
     zbl = {0326.39008},
     url = {http://geodesic.mathdoc.fr/item/AM2_1976__14_136613/}
}