@article{AM2_1997__54_3_137706,
     author = {Thomas Riedel and Prasanna K. Sahoo},
     title = {On two functional equations connected with the characterizations of the distance measures.},
     journal = {Aequationes mathematicae},
     pages = {242--263},
     publisher = {mathdoc},
     volume = {54},
     number = {3},
     year = {1997},
     zbl = {0895.39007},
     url = {http://geodesic.mathdoc.fr/item/AM2_1997__54_3_137706/}
}