@article{AM2_1991__41_2-3_137390,
     author = {Marek Kuczma},
     title = {On the quasiarithmetic mean in a mean value property and the associated functional equation.},
     journal = {Aequationes mathematicae},
     pages = {33--54},
     publisher = {mathdoc},
     volume = {41},
     number = {2-3},
     year = {1991},
     zbl = {0726.39003},
     url = {http://geodesic.mathdoc.fr/item/AM2_1991__41_2-3_137390/}
}