@article{AM2_1990__40_1_137378,
     author = {H. Haruki},
     title = {A new {Pythagorean} functional equation.},
     journal = {Aequationes mathematicae},
     pages = {271--280},
     publisher = {mathdoc},
     volume = {40},
     number = {1},
     year = {1990},
     zbl = {0722.30012},
     url = {http://geodesic.mathdoc.fr/item/AM2_1990__40_1_137378/}
}