@article{AM2_1993__45_2-3_137529,
     author = {Jens Schwaiger and Wolfgang F\"org-Rob},
     title = {On the stabiltiy of a system of functional equations characterizing generalize hyperbolic and trigonometric functions.},
     journal = {Aequationes mathematicae},
     pages = {285--296},
     publisher = {mathdoc},
     volume = {45},
     number = {2-3},
     year = {1993},
     zbl = {0774.39007},
     url = {http://geodesic.mathdoc.fr/item/AM2_1993__45_2-3_137529/}
}