@article{AM2_1990__39_2-3_137340,
     author = {C.T. Ng},
     title = {Jensen's functional equation on groups.},
     journal = {Aequationes mathematicae},
     pages = {85--99},
     publisher = {mathdoc},
     volume = {39},
     number = {2-3},
     year = {1990},
     zbl = {0688.39007},
     url = {http://geodesic.mathdoc.fr/item/AM2_1990__39_2-3_137340/}
}