@article{AM2_1980__21_182433,
     author = {Peter Kardos},
     title = {A generalization of {Bellman's} functional equation.},
     journal = {Aequationes mathematicae},
     pages = {236--245},
     publisher = {mathdoc},
     volume = {21},
     year = {1980},
     zbl = {0467.39003},
     url = {http://geodesic.mathdoc.fr/item/AM2_1980__21_182433/}
}