@article{GDZPPN002195313,
title = {The functional equation F(ax) + F(bx+a) = F(bx) + F(ax+b), entire and almost periodic solutions.},
journal = {Journal f\"ur die reine und angewandte Mathematik},
volume = {302},
year = {1978},
pages = {116-136},
zbl = {0376.39003},
url = {http://dml.mathdoc.fr/item/GDZPPN002195313}
}
Ryff, John V. The functional equation F(ax) + F(bx+a) = F(bx) + F(ax+b), entire and almost periodic solutions.. Journal für die reine und angewandte Mathematik, Tome 302 (1978) pp. 116-136. http://gdmltest.u-ga.fr/item/GDZPPN002195313/