@article{MZ_1968__104_170952,
     author = {Hiroshi Haruki},
     title = {On {Parallelogram} {Functional} {Equations.}},
     journal = {Mathematische Zeitschrift},
     pages = {358--363},
     publisher = {mathdoc},
     volume = {104},
     year = {1968},
     zbl = {0153.45803},
     url = {http://geodesic.mathdoc.fr/item/MZ_1968__104_170952/}
}