@article{GDZPPN002038021, title = {Jensen's functional equation on groups.}, journal = {Aequationes mathematicae}, volume = {40}, year = {1990}, pages = {85-99}, zbl = {0688.39007}, url = {http://dml.mathdoc.fr/item/GDZPPN002038021} }
Ng, C.T. Jensen's functional equation on groups.. Aequationes mathematicae, Tome 40 (1990) pp. 85-99. http://gdmltest.u-ga.fr/item/GDZPPN002038021/