@article{GDZPPN002038412,
title = {A new Pythagorean functional equation.},
journal = {Aequationes mathematicae},
volume = {40},
year = {1990},
pages = {271-280},
zbl = {0722.30012},
url = {http://dml.mathdoc.fr/item/GDZPPN002038412}
}
Haruki, H. A new Pythagorean functional equation.. Aequationes mathematicae, Tome 40 (1990) pp. 271-280. http://gdmltest.u-ga.fr/item/GDZPPN002038412/