@article{AM2_1985__28_137065,
     author = {Marek Kuczma and Bogdan Choczewski},
     title = {On a system of functional equations.},
     journal = {Aequationes mathematicae},
     pages = {262--268},
     publisher = {mathdoc},
     volume = {28},
     year = {1985},
     zbl = {0571.39001},
     url = {http://geodesic.mathdoc.fr/item/AM2_1985__28_137065/}
}