@article{AM2_1987__32_137189,
     author = {Istv\'an Feny\"o},
     title = {On the hyperbolic linear functional equations.},
     journal = {Aequationes mathematicae},
     pages = {252--258},
     publisher = {mathdoc},
     volume = {32},
     year = {1987},
     zbl = {0623.39006},
     url = {http://geodesic.mathdoc.fr/item/AM2_1987__32_137189/}
}